










                         SENDMAILTM

              INSTALLATION AND OPERATION GUIDE

                        Eric Allman
                    Gregory Neil Shapiro
                       Claus Assmann
                       Sendmail, Inc.

                     Version 8.609.2.5

                 For Sendmail Version 8.12




     SendmailTM  implements  a  general purpose internetwork
mail routing facility under the  UNIX(R)  operating  system.
It is not tied to any one transport protocol -- its function
may be likened to a crossbar switch, relaying messages  from
one  domain  into another.  In the process, it can do a lim-
ited amount of message header editing  to  put  the  message
into  a format that is appropriate for the receiving domain.
All of this is done under the  control  of  a  configuration
file.

     Due  to  the  requirements of flexibility for sendmail,
the configuration file  can  seem  somewhat  unapproachable.
However,  there are only a few basic configurations for most
sites, for which standard configuration files have been sup-
plied.   Most other configurations can be built by adjusting
an existing configuration file incrementally.

     Sendmail is based on RFC  821  (Simple  Mail  Transport
Protocol),  RFC  822 (Internet Mail Headers Format), RFC 974
(MX routing), RFC 1123  (Internet  Host  Requirements),  RFC
1413 (Identification server), RFC 1652 (SMTP 8BITMIME Exten-
sion), RFC 1869 (SMTP Service Extensions),  RFC  1870  (SMTP
SIZE  Extension),  RFC  1891 (SMTP Delivery Status Notifica-
tions), RFC 1892 (Multipart/Report), RFC 1893 (Enhanced Mail
System  Status  Codes),  RFC 1894 (Delivery Status Notifica-
tions), RFC 1985 (SMTP Service Extension for Remote  Message
Queue Starting), RFC 2033 (Local Message Transmission Proto-
col),  RFC  2034  (SMTP  Service  Extension  for   Returning
____________________
   DISCLAIMER: This documentation is under modification.
   Sendmail is a trademark of Sendmail, Inc.




Sendmail Installation and Operation Guide           SMM:08-1







SMM:08-2           Sendmail Installation and Operation Guide


Enhanced  Error  Codes),  RFC 2045 (MIME), RFC 2476 (Message
Submission), RFC 2487 (SMTP  Service  Extension  for  Secure
SMTP over TLS), RFC 2554 (SMTP Service Extension for Authen-
tication), RFC 2821 (Simple  Mail  Transfer  Protocol),  RFC
2822  (Internet  Message  Format), RFC 2852 (Deliver By SMTP
Service Extension), and RFC 2920 (SMTP Service Extension for
Command Pipelining).  However, since sendmail is designed to
work in a wider world, in many cases it can be configured to
exceed these protocols.  These cases are described herein.

     Although  sendmail  is intended to run without the need
for monitoring, it has a number of features that may be used
to  monitor  or  adjust  the operation under unusual circum-
stances.  These features are described.

     Section one  describes  how  to  do  a  basic  sendmail
installation.   Section two explains the day-to-day informa-
tion you should know to maintain your mail system.   If  you
have  a  relatively  normal  site, these two sections should
contain sufficient information for you to  install  sendmail
and  keep it happy.  Section three has information regarding
the command line arguments.   Section  four  describes  some
parameters  that  may  be safely tweaked.  Section five con-
tains the nitty-gritty information about  the  configuration
file.   This  section  is for masochists and people who must
write their own configuration file.  Section  six  describes
configuration  that  can  be  done  at  compile  time.   The
appendixes give a brief but detailed explanation of a number
of features not described in the rest of the paper.


































Sendmail Installation and Operation Guide           SMM:08-7


1.  BASIC INSTALLATION

        There  are  two  basic steps to installing sendmail.
   First, you have to compile and install  the  binary.   If
   sendmail has already been ported to your operating system
   that should be simple.  Second, you must build a run-time
   configuration  file.   This is a file that sendmail reads
   when it starts up that describes  the  mailers  it  knows
   about, how to parse addresses, how to rewrite the message
   header, and the settings of  various  options.   Although
   the configuration file can be quite complex, a configura-
   tion can usually be built using an M4-based configuration
   language.   Assuming  you have the standard sendmail dis-
   tribution, see cf/README for further information.

        The remainder of  this  section  will  describe  the
   installation  of sendmail assuming you can use one of the
   existing configurations and that the  standard  installa-
   tion  parameters are acceptable.  All pathnames and exam-
   ples are given from the root  of  the  sendmail  subtree,
   normally  /usr/src/usr.sbin/sendmail on 4.4BSD-based sys-
   tems.

        Continue with the next section if you  need/want  to
   compile  sendmail yourself.  If you have a running binary
   already on your system, you should probably skip to  sec-
   tion 1.2.

   1.1.  Compiling Sendmail

           All  sendmail source is in the sendmail subdirec-
      tory.  To compile sendmail,  "cd"  into  the  sendmail
      directory and type

          ./Build

      This  will  leave the binary in an appropriately named
      subdirectory, e.g., obj.BSD-OS.2.1.i386.  It works for
      multiple  object  versions  compiled  out  of the same
      directory.

      1.1.1.  Tweaking the Build Invocation

              You can give parameters on the Build  command.
         In  most  cases  these are only used when the obj.*
         directory  is  first  created.   To  restart   from
         scratch, use -c.  These commands include:

         -L libdirs
              A list of directories to search for libraries.

         -I incdirs
              A list of directories to  search  for  include










SMM:08-8           Sendmail Installation and Operation Guide


              files.

         -E envar=value
              Set  an  environment  variable to an indicated
              value before compiling.

         -c   Create a new obj.*  tree before running.

         -f siteconfig
              Read the indicated  site  configuration  file.
              If  this  parameter  is  not  specified, Build
              includes   all   of    the    files    $BUILD-
              TOOLS/Site/site.$oscf.m4      and      $BUILD-
              TOOLS/Site/site.config.m4,  where  $BUILDTOOLS
              is  normally ../devtools and $oscf is the same
              name as used on  the  obj.*   directory.   See
              below for a description of the site configura-
              tion file.

         -S   Skip  auto-configuration.   Build  will  avoid
              auto-detecting  libraries if this is set.  All
              libraries and map definitions must  be  speci-
              fied in the site configuration file.

         Most  other  parameters are passed to the make pro-
         gram; for details see $BUILDTOOLS/README.

      1.1.2.  Creating a Site Configuration File

              (This section is not yet complete.   For  now,
         see  the  file  devtools/README  for details.)  See
         sendmail/README for various compilation flags  that
         can be set.

      1.1.3.  Tweaking the Makefile

              Sendmail  supports  two  different formats for
         the local (on disk) version of  databases,  notably
         the aliases database.  At least one of these should
         be defined if at all possible.

         NDBM      The  ``new  DBM''  format,  available  on
                   nearly  all  systems  around today.  This
                   was the preferred format prior to 4.4BSD.
                   It allows such complex things as multiple
                   databases and closing  a  currently  open
                   database.

         NEWDB     The  Berkeley  DB  package.   If you have
                   this, use it.  It  allows  long  records,
                   multiple  open  databases, real in-memory
                   caching, and so forth.   You  can  define
                   this in conjunction with NDBM; if you do,










Sendmail Installation and Operation Guide           SMM:08-9


                   old alias databases are read, but when  a
                   new  database  is  created  it will be in
                   NEWDB format.  As a nasty  hack,  if  you
                   have NEWDB, NDBM, and NIS defined, and if
                   the alias file  name  includes  the  sub-
                   string  "/yp/", sendmail will create both
                   new and old versions of  the  alias  file
                   during   a  newalias  command.   This  is
                   required because the  Sun  NIS/YP  system
                   reads  the DBM version of the alias file.
                   It's ugly as sin, but it works.

         If neither of these are defined, sendmail reads the
         alias  file  into memory on every invocation.  This
         can be slow and should be avoided.  There are  also
         several methods for remote database access:

         LDAP      Lightweight Directory Access Protocol.

         NIS       Sun's  Network Information Services (for-
                   merly YP).

         NISPLUS   Sun's NIS+ services.

         NETINFO   NeXT's NetInfo service.

         HESIOD    Hesiod service (from Athena).

         Other compilation  flags  are  set  in  conf.h  and
         should be predefined for you unless you are porting
         to a new environment.  For more options  see  send-
         mail/README.

      1.1.4.  Compilation and installation

              After  making  the  local system configuration
         described above, You should be able to compile  and
         install the system.  The script "Build" is the best
         approach on most systems:

             ./Build

         This will use uname(1) to create a custom  Makefile
         for your environment.

              If  you are installing in the standard places,
         you should be able to install using

             ./Build install

         This should install the  binary  in  /usr/sbin  and
         create    links    from   /usr/bin/newaliases   and
         /usr/bin/mailq  to  /usr/sbin/sendmail.   On   most










SMM:08-10          Sendmail Installation and Operation Guide


         systems  it will also format and install man pages.
         Notice: as of version 8.12 sendmail will no  longer
         be  installed  set-user-ID root by default.  If you
         really want to use the old method, you can  specify
         it as target:

             ./Build install-set-user-id


   1.2.  Configuration Files

           Sendmail  cannot  operate without a configuration
      file.  The configuration  defines  the  mail  delivery
      mechanisms  understood  at  this  site,  how to access
      them, how to forward email to remote mail systems, and
      a  number  of  tuning  parameters.  This configuration
      file is detailed in the later portion  of  this  docu-
      ment.

           The  sendmail  configuration  can  be daunting at
      first.  The world is complex, and the mail  configura-
      tion  reflects  that.   The  distribution  includes an
      m4-based configuration package that hides a lot of the
      complexity.  See cf/README for details.

           Our  configuration  files  are processed by m4 to
      facilitate local customization; the  directory  cf  of
      the   sendmail  distribution  directory  contains  the
      source files.  This directory contains several  subdi-
      rectories:

      cf        Both   site-dependent  and  site-independent
                descriptions of hosts.  These can be literal
                host  names  (e.g.,  "ucbvax.mc")  when  the
                hosts are gateways or more general  descrip-
                tions  (such  as  "generic-solaris2.mc" as a
                general  description  of  an  SMTP-connected
                host  running Solaris 2.x.  Files ending .mc
                (``M4   Configuration'')   are   the   input
                descriptions;  the  output  is in the corre-
                sponding .cf file.  The general structure of
                these files is described below.

      domain    Site-dependent    subdomain    descriptions.
                These are tied to the way your  organization
                wants   to   do  addressing.   For  example,
                domain/CS.Berkeley.EDU.m4 is our description
                for  hosts in the CS.Berkeley.EDU subdomain.
                These are referenced  using  the  DOMAIN  m4
                macro in the .mc file.

      feature   Definitions  of  specific features that some
                particular host in  your  site  might  want.










Sendmail Installation and Operation Guide          SMM:08-11


                These  are  referenced  using the FEATURE m4
                macro.  An example  feature  is  use_cw_file
                (which    tells    sendmail   to   read   an
                /etc/mail/local-host-names file  on  startup
                to find the set of local names).

      hack      Local  hacks,  referenced  using the HACK m4
                macro.  Try to avoid these.   The  point  of
                having  them  here  is to make it clear that
                they smell.

      m4        Site-independent m4(1)  include  files  that
                have information common to all configuration
                files.   This  can  be  thought  of   as   a
                "#include" directory.

      mailer    Definitions of mailers, referenced using the
                MAILER m4 macro.  The mailer types that  are
                known  in  this distribution are fax, local,
                smtp, uucp, and  usenet.   For  example,  to
                include  support for the UUCP-based mailers,
                use "MAILER(uucp)".

      ostype    Definitions  describing  various   operating
                system environments (such as the location of
                support files).  These are referenced  using
                the OSTYPE m4 macro.

      sh        Shell  files  used  by the m4 build process.
                You shouldn't have to mess with these.

      siteconfig
                Local UUCP connectivity  information.   This
                directory  has  been supplanted by the mail-
                ertable  feature;  any  new   configurations
                should  use  that  feature  to  do UUCP (and
                other) routing.  The use of  this  directory
                is deprecated.

           If you are in a new domain (e.g., a company), you
      will probably want to create a cf/domain file for your
      domain.   This consists primarily of relay definitions
      and features you want enabled site-wide: for  example,
      Berkeley's domain definition defines relays for BitNET
      and UUCP.  These are specific to Berkeley, and  should
      be   fully-qualified   internet-style   domain  names.
      Please check to make certain they are  reasonable  for
      your domain.

           Subdomains  at  Berkeley  are also represented in
      the cf/domain  directory.   For  example,  the  domain
      CS.Berkeley.EDU  is  the  Computer  Science subdomain,
      EECS.Berkeley.EDU is the  Electrical  Engineering  and










SMM:08-12          Sendmail Installation and Operation Guide


      Computer  Sciences  subdomain, and S2K.Berkeley.EDU is
      the Sequoia 2000 subdomain.  You will probably have to
      add  an  entry to this directory to be appropriate for
      your domain.

           You will have to use or create .mc files  in  the
      cf/cf  subdirectory  for your hosts.  This is detailed
      in the cf/README file.

   1.3.  Details of Installation Files

           This subsection describes the files that comprise
      the sendmail installation.

      1.3.1.  /usr/sbin/sendmail

              The   binary   for   sendmail  is  located  in
         /usr/sbin1.  It should  be  set-group-ID  smmsp  as
         described  in sendmail/SECURITY.  For security rea-
         sons, /, /usr, and /usr/sbin  should  be  owned  by
         root, mode 07552.

      1.3.2.  /etc/mail/sendmail.cf

              This  is the main configuration file for send-
         mail3.  This is one of  the  two  non-library  file
         names   compiled   into  sendmail4,  the  other  is
         /etc/mail/submit.cf.

              The configuration  file  is  normally  created
         using  the  distribution files described above.  If
         you   have   a    particularly    unusual    system
____________________
   1This is usually /usr/sbin on 4.4BSD and  newer  systems;
many  systems install it in /usr/lib.  I understand it is in
/usr/ucblib on System V Release 4.
   2Some  vendors ship them owned by bin; this creates a se-
curity hole that is not actually related to sendmail.  Other
important  directories  that  should have restrictive owner-
ships and permissions are /bin, /usr/bin,  /etc,  /etc/mail,
/usr/etc, /lib, and /usr/lib.
   3Actually, the pathname varies depending on the operating
system;  /etc/mail  is  the preferred directory.  Some older
systems install it in /usr/lib/sendmail.cf,  and  I've  also
seen  it in /usr/ucblib.  If you want to move this file, add
-D_PATH_SENDMAILCF=\"/file/name\" to the flags passed to the
C compiler.  Moving this file is not recommended: other pro-
grams and scripts know of this location.
   4The system libraries can reference other files; in  par-
ticular,  system  library  subroutines  that  sendmail calls
probably reference /etc/passwd and /etc/resolv.conf.












Sendmail Installation and Operation Guide          SMM:08-13


         configuration you may need to create a special ver-
         sion.  The format of this file is detailed in later
         sections of this document.

      1.3.3.  /etc/mail/submit.cf

              This  is  the  configuration file for sendmail
         when it is used for  initial  mail  submission,  in
         which case it is also called ``Mail Submission Pro-
         gram'' (MSP) in contrast to ``Mail Transfer Agent''
         (MTA).   Starting  with version 8.12, sendmail uses
         one of two different configuration files  based  on
         its  operation  mode  (or  the new -A option).  For
         initial  mail  submission,  i.e.,  if  one  of  the
         options  -bm  (default),  -bs,  or -t is specified,
         submit.cf is used (if available), for other  opera-
         tions sendmail.cf is used.  Details can be found in
         sendmail/SECURITY.  submit.cf is shipped with send-
         mail  (in  cf/cf/) and is installed by default.  If
         changes to the configuration need to be made, start
         with  cf/cf/submit.mc and follow the instruction in
         cf/README.

      1.3.4.  /usr/bin/newaliases

              The newaliases command should just be  a  link
         to sendmail:

             rm -f /usr/bin/newaliases
             ln -s /usr/sbin/sendmail /usr/bin/newaliases

         This  can  be installed in whatever search path you
         prefer for your system.

      1.3.5.  /usr/bin/hoststat

              The hoststat command should just be a link  to
         sendmail, in a fashion similar to newaliases.  This
         command lists the status of the last mail  transac-
         tion  with all remote hosts.  The -v flag will pre-
         vent the status display from being  truncated.   It
         functions  only when the HostStatusDirectory option
         is set.

      1.3.6.  /usr/bin/purgestat

              This command is also a link to  sendmail.   It
         flushes  expired  (Timeout.hoststatus)  information
         that is stored in the HostStatusDirectory tree.














SMM:08-14          Sendmail Installation and Operation Guide


      1.3.7.  /var/spool/mqueue

              The directory /var/spool/mqueue should be cre-
         ated to hold the mail queue.  This directory should
         be mode 0700 and owned by root.

              The actual path of this directory  is  defined
         by  the  QueueDirectory  option  of the sendmail.cf
         file.  To use multiple queues, supply a value  end-
         ing     with    an    asterisk.     For    example,
         /var/spool/mqueue/qd* will use all of the  directo-
         ries  or  symbolic  links  to directories beginning
         with `qd' in /var/spool/mqueue  as  queue  directo-
         ries.   Do not change the queue directory structure
         while sendmail is running.

              If these directories  have  subdirectories  or
         symbolic links to directories named `qf', `df', and
         `xf', then these will be  used  for  the  different
         queue  file  types.   That  is,  the data files are
         stored in the  `df'  subdirectory,  the  transcript
         files  are stored in the `xf' subdirectory, and all
         others are stored in the `qf' subdirectory.

              If shared memory support is compiled in, send-
         mail  stores  the  available  diskspace in a shared
         memory segment to make the values readily available
         to  all children without incurring system overhead.
         In this case, only the  daemon  updates  the  data;
         i.e., the sendmail daemon creates the shared memory
         segment and deletes it if it is terminated.  To use
         this, sendmail must have been compiled with support
         for shared memory (-DSM_CONF_SHM)  and  the  option
         SharedMemoryKey  must  be  set.  Notice: do not use
         the same key for sendmail invocations with  differ-
         ent queue directories or different queue group dec-
         larations.  Access to shared  memory  is  not  con-
         trolled  by  locks, i.e., there is a race condition
         when data in the shared memory  is  updated.   How-
         ever,  since operation of sendmail does not rely on
         the data in the shared memory, this does not  nega-
         tively influence the behavior.

      1.3.8.  /var/spool/clientmqueue

              The  directory  /var/spool/clientmqueue should
         be created to hold the mail queue.  This  directory
         should  be mode 0770 and owned by user smmsp, group
         smmsp.

              The actual path of this directory  is  defined
         by the QueueDirectory option of the submit.cf file.











Sendmail Installation and Operation Guide          SMM:08-15


      1.3.9.  /var/spool/mqueue/.hoststat

              This is a typical value for the  HostStatusDi-
         rectory  option,  containing one file per host that
         this sendmail has chatted  with  recently.   It  is
         normally a subdirectory of mqueue.

      1.3.10.  /etc/mail/aliases*

              The     system    aliases    are    held    in
         "/etc/mail/aliases".  A sample is given  in  "send-
         mail/aliases"  which  includes  some  aliases which
         must be defined:

             cp sendmail/aliases /etc/mail/aliases
             edit /etc/mail/aliases

         You should extend this file with any  aliases  that
         are apropos to your system.

              Normally  sendmail looks at a database version
         of     the     files,     stored     either      in
         "/etc/mail/aliases.dir" and "/etc/mail/aliases.pag"
         or  "/etc/mail/aliases.db"   depending   on   which
         database package you are using.  The actual path of
         this file is defined in the AliasFile option of the
         sendmail.cf file.

              The  permissions  of  the  alias  file and the
         database versions should be 0640 to  prevent  local
         denial  of  service attacks as explained in the top
         level README in the sendmail distribution.  If  the
         permissions  0640  are  used,  be  sure  that  only
         trusted users belong to the group assigned to those
         files.   Otherwise,  files should not even be group
         readable.

      1.3.11.  /etc/rc or /etc/init.d/sendmail

              It will be necessary to start up the  sendmail
         daemon  when your system reboots.  This daemon per-
         forms two functions: it listens on the SMTP  socket
         for connections (to receive mail from a remote sys-
         tem) and it processes  the  queue  periodically  to
         insure that mail gets delivered when hosts come up.

              If  necessary,  add  the  following  lines  to
         "/etc/rc"  (or  "/etc/rc.local"  as appropriate) in
         the area where it is starting up the daemons  on  a
         BSD-base  system,  or on a System-V-based system in
         one    of    the    startup    files,     typically
         "/etc/init.d/sendmail":











SMM:08-16          Sendmail Installation and Operation Guide


             if [ -f /usr/sbin/sendmail -a -f /etc/mail/sendmail.cf ]; then
                  (cd /var/spool/mqueue; rm -f xf*)
                  /usr/sbin/sendmail -bd -q30m &
                  echo -n ' sendmail' >/dev/console
             fi

         The  "cd"  and  "rm" commands insure that all tran-
         script files have been  removed;  extraneous  tran-
         script  files may be left around if the system goes
         down in the middle of processing  a  message.   The
         line  that actually invokes sendmail has two flags:
         "-bd" causes it to listen on  the  SMTP  port,  and
         "-q30m" causes it to run the queue every half hour.

              Some people use a more complex startup script,
         removing  zero  length  qf  files  and df files for
         which there is no qf file.  For example, see Figure
         1  for  an  example  of a complex script which does
         this clean up.

      1.3.12.  /etc/mail/helpfile

              This is the help file used by  the  SMTP  HELP
         command.   It should be copied from "sendmail/help-
         file":

             cp sendmail/helpfile /etc/mail/helpfile

         The actual path of this  file  is  defined  in  the
         HelpFile option of the sendmail.cf file.

      1.3.13.  /etc/mail/statistics

              If  you  wish to collect statistics about your
         mail  traffic,   you   should   create   the   file
         "/etc/mail/statistics":

             cp /dev/null /etc/mail/statistics
             chmod 0600 /etc/mail/statistics

         This  file  does  not grow.  It is printed with the
         program "mailstats/mailstats.c."  The  actual  path
         of  this  file  is  defined  in the S option of the
         sendmail.cf file.

      1.3.14.  /usr/bin/mailq

              If sendmail is invoked  as  "mailq,"  it  will
         simulate  the  -bp  flag (i.e., sendmail will print
         the contents of the mail queue; see  below).   This
         should be a link to /usr/sbin/sendmail.












Sendmail Installation and Operation Guide          SMM:08-17



____________________________________________________________

#!/bin/sh
# remove zero length qf files
for qffile in qf*
do
     if [ -r $qffile ]
     then
          if [ ! -s $qffile ]
          then
               echo -n " <zero: $qffile>" > /dev/console
               rm -f $qffile
          fi
     fi
done
# rename tf files to be qf if the qf does not exist
for tffile in tf*
do
     qffile=`echo $tffile | sed 's/t/q/'`
     if [ -r $tffile -a ! -f $qffile ]
     then
          echo -n " <recovering: $tffile>" > /dev/console
          mv $tffile $qffile
     else
          if [ -f $tffile ]
          then
               echo -n " <extra: $tffile>" > /dev/console
               rm -f $tffile
          fi
     fi
done
# remove df files with no corresponding qf files
for dffile in df*
do
     qffile=`echo $dffile | sed 's/d/q/'`
     if [ -r $dffile -a ! -f $qffile ]
     then
          echo -n " <incomplete: $dffile>" > /dev/console
          mv $dffile `echo $dffile | sed 's/d/D/'`
     fi
done
# announce files that have been saved during disaster recovery
for xffile in [A-Z]f*
do
     if [ -f $xffile ]
     then
          echo -n " <panic: $xffile>" > /dev/console
     fi
done

            Figure 1 -- A complex startup script
____________________________________________________________










SMM:08-18          Sendmail Installation and Operation Guide


      1.3.15.  sendmail.pid

              sendmail  stores  its  current pid in the file
         specifed  by  the  PidFile   option   (default   is
         _PATH_SENDMAILPID).    sendmail  uses  TempFileMode
         (which defaults to 0600) as the permissions of that
         file  to prevent local denial of service attacks as
         explained in the top level README in  the  sendmail
         distribution.   If the file already exists, then it
         might  be  necessary  to  change  the   permissions
         accordingly, e.g.,

             chmod 0600 /var/run/sendmail.pid


      1.3.16.  Map Files

              To  prevent local denial of service attacks as
         explained in the top level README in  the  sendmail
         distribution,  the permissions of map files created
         by makemap should be 0640.  The use of 0640 implies
         that   only  trusted  users  belong  to  the  group
         assigned to those files.  If  those  files  already
         exist,  then  it  might  be necessary to change the
         permissions accordingly, e.g.,

             cd /etc/mail
             chmod 0640 *.db *.pag *.dir


2.  NORMAL OPERATIONS

   2.1.  The System Log

           The system log is  supported  by  the  syslogd(8)
      program.   All messages from sendmail are logged under
      the LOG_MAIL facility5.

      2.1.1.  Format

              Each  line  in  the  system  log consists of a
         timestamp, the name of the machine  that  generated
         it  (for  logging  from  several  machines over the
         local area network), the word  "sendmail:",  and  a
         message6.   Most  messages  are   a   sequence   of
         name=value pairs.
____________________
   5Except on Ultrix, which does not support  facilities  in
the syslog.
   6This format may vary slightly if your vendor has changed
the syntax.












Sendmail Installation and Operation Guide          SMM:08-19


              The  two  most  common lines are logged when a
         message is processed.  The first logs  the  receipt
         of  a  message;  there will be exactly one of these
         per message.  Some fields may be omitted if they do
         not contain interesting information.  Fields are:

         from      The envelope sender address.

         size      The size of the message in bytes.

         class     The  class  (i.e., numeric precedence) of
                   the message.

         pri       The initial message  priority  (used  for
                   queue sorting).

         nrcpts    The  number  of  envelope  recipients for
                   this message (after aliasing and forward-
                   ing).

         msgid     The  message  id of the message (from the
                   header).

         proto     The protocol used to receive this message
                   (e.g., ESMTP or UUCP)

         daemon    The  daemon  name  from the DaemonPortOp-
                   tions setting.

         relay     The machine from which it was received.

         There is also one line logged per delivery  attempt
         (so there can be several per message if delivery is
         deferred or there are multiple recipients).  Fields
         are:

         to        A  comma-separated list of the recipients
                   to this mailer.

         ctladdr   The ``controlling user'',  that  is,  the
                   name of the user whose credentials we use
                   for delivery.

         delay     The total delay  between  the  time  this
                   message  was  received  and  the  current
                   delivery attempt.

         xdelay    The amount of time needed in this  deliv-
                   ery  attempt  (normally indicative of the
                   speed of the connection).

         mailer    The name of the mailer used to deliver to
                   this recipient.










SMM:08-20          Sendmail Installation and Operation Guide


         relay     The   name  of  the  host  that  actually
                   accepted (or rejected) this recipient.

         dsn       The enhanced error  code  (RFC  2034)  if
                   available.

         stat      The delivery status.

         Not  all  fields  are  present in all messages; for
         example, the relay is usually not listed for  local
         deliveries.

      2.1.2.  Levels

              If   you  have  syslogd(8)  or  an  equivalent
         installed, you will be able to do  logging.   There
         is  a  large  amount  of  information  that  can be
         logged.  The log is arranged  as  a  succession  of
         levels.  At the lowest level only extremely strange
         situations are logged.  At the highest level,  even
         the  most  mundane  and  uninteresting  events  are
         recorded for posterity.  As a convention, log  lev-
         els  under  ten  are considered generally "useful;"
         log levels above 64 are reserved for debugging pur-
         poses.   Levels from 11-64 are reserved for verbose
         information that some sites might want.

              A complete description of the  log  levels  is
         given in section 4.6.

   2.2.  Dumping State

           You  can  ask  sendmail to log a dump of the open
      files and the connection cache by sending it a SIGUSR1
      signal.  The results are logged at LOG_DEBUG priority.

   2.3.  The Mail Queues

           Mail messages may either be delivered immediately
      or  be  held  for  later  delivery.  Held messages are
      placed into a holding directory called a mail queue.

           A mail message may be queued for these reasons:

       + If a mail message is temporarily undeliverable,  it
         is  queued and delivery is attempted later.  If the
         message is addressed to multiple recipients, it  is
         queued  only  for those recipients to whom delivery
         is not immediately possible.
       + If the SuperSafe option is set to  true,  all  mail
         messages are queued while delivery is attempted.
       + If  the DeliveryMode option is set to queue-only or
         defer,  all  mail  is  queued,  and  no   immediate










Sendmail Installation and Operation Guide          SMM:08-21


         delivery is attempted.
       + If  the  load average becomes higher than the value
         of the  QueueLA  option  and  the  QueueFactor  (q)
         option  divided  by  the  difference in the current
         load average and the QueueLA  option  plus  one  is
         less than the priority of the message, messages are
         queued rather than immediately delivered.

      2.3.1.  Queue Groups and Queue Directories

              There are one or more mail queues.  Each  mail
         queue  belongs to a queue group.  There is always a
         default  queue  group  that  is  called  ``mqueue''
         (which  is where messages go by default unless oth-
         erwise specified).  The  directory  or  directories
         which  comprise  the default queue group are speci-
         fied by the QueueDirectory option.  There are  zero
         or  more  additional  named  queue  groups declared
         using the Q command in the configuration file.

              By default, a queued message is placed in  the
         queue  group associated with the first recipient in
         the recipient list.  A recipient address is  mapped
         to  a queue group as follows.  First, if there is a
         ruleset called ``queuegroup'', and if this  ruleset
         maps  the  address to a queue group name, then that
         queue group is chosen.  That is, the  argument  for
         the ruleset is the recipient address and the result
         should be $# followed by the name of a queue group.
         Otherwise,   if  the  mailer  associated  with  the
         address specifies a queue group,  then  that  queue
         group  is  chosen.   Otherwise,  the  default queue
         group is chosen.

              A message with  multiple  recipients  will  be
         split  if  different queue groups are chosen by the
         mapping of recipients to queue groups.

              When a message is placed in a queue group, and
         the queue group has more than one queue, a queue is
         selected randomly.

              If  a  message  with  multiple  recipients  is
         placed into a queue group with the 'r' option (max-
         imum number of recipients per  message)  set  to  a
         positive  value  N,  and  if  there are more than N
         recipients in the message, then the message will be
         split into multiple messages, each of which have at
         most N recipients.

              Notice: if multiple queue groups are used,  do
         not move queue files around, e.g., into a different
         queue directory.  This may have weird  effects  and










SMM:08-22          Sendmail Installation and Operation Guide


         can  cause  mail  not to be delivered.  Queue files
         and directories should be  treated  as  opaque  and
         should not be manipulated directly.

      2.3.2.  Queue Runs

              sendmail has two different ways to process the
         queue(s).  The first one is to start queue  runners
         after certain intervals (``normal'' queue runners),
         the second one is to keep  queue  runner  processes
         around  (``persistent''  queue  runners).   How  to
         select either of these types is  discussed  in  the
         appendix  ``COMMAND LINE FLAGS''.  Persistent queue
         runners have the advantage that  no  new  processes
         need  to be spawned at certain intervals; they just
         sleep for a specified time after  they  finished  a
         queue  run.   Another advantage of persistent queue
         runners is that only one  process  belonging  to  a
         workgroup  (a  workgroup  is a set of queue groups)
         collects the data for a queue run and then multiple
         queue  runner  may  go ahead using that data.  This
         can significantly reduce the disk I/O necessary  to
         read  the queue files compared to starting multiple
         queue runners directly.  Their disadvantage is that
         a  new  queue  run  is only started after all queue
         runners belonging to a group finished their  tasks.
         In  case one of the queue runners tries delivery to
         a slow recipient site at the end of  a  queue  run,
         the  next  queue  run may be substantially delayed.
         In general this should be smoothed out due  to  the
         distribution of those slow jobs, however, for sites
         with small  number  of  queue  entries  this  might
         introduce noticable delays.  In general, persistent
         queue runners are only useful for  sites  with  big
         queues.

      2.3.3.  Manual Intervention

              Under normal conditions the mail queue will be
         processed transparently.   However,  you  may  find
         that  manual  intervention  is sometimes necessary.
         For example, if a major host is down for  a  period
         of  time  the  queue  may become clogged.  Although
         sendmail ought to recover gracefully when the  host
         comes up, you may find performance unacceptably bad
         in the meantime.  In that case you  want  to  check
         the  content  of  the  queue  and  manipulate it as
         explained in the next two sections.

      2.3.4.  Printing the queue

              The contents of the queue(s)  can  be  printed
         using  the  mailq command (or by specifying the -bp










Sendmail Installation and Operation Guide          SMM:08-23


         flag to sendmail):

             mailq

         This will produce a listing of the queue id's,  the
         size  of  the message, the date the message entered
         the queue,  and  the  sender  and  recipients.   If
         shared  memory support is compiled in, the flag -bP
         can be used to print the number of entries  in  the
         queue(s),  provided  a  process  updates  the data.
         However, as explained earlier, the output might  be
         slightly  wrong,  since access to the shared memory
         is not locked.  For example,  ``unknown  number  of
         entries''  might  be  shown.  The internal counters
         are updated after each queue  run  to  the  correct
         value again.

      2.3.5.  Forcing the queue

              Sendmail should run the queue automatically at
         intervals.  When using multiple queues, a  separate
         process  will  by default be created to run each of
         the queues unless the queue run is initiated  by  a
         user  with  the  verbose flag.  The algorithm is to
         read and sort the queue, and  then  to  attempt  to
         process all jobs in order.  When it attempts to run
         the job, sendmail first checks to see if the job is
         locked.  If so, it ignores the job.

              There  is  no  attempt to insure that only one
         queue processor exists at any time, since there  is
         no guarantee that a job cannot take forever to pro-
         cess (however, sendmail does include heuristics  to
         try to abort jobs that are taking absurd amounts of
         time; technically, this violates RFC  821,  but  is
         blessed  by  RFC  1123).   Due to the locking algo-
         rithm, it is impossible for one job to  freeze  the
         entire  queue.  However, an uncooperative recipient
         host or a program recipient that never returns  can
         accumulate many processes in your system.  Unfortu-
         nately, there is no completely general way to solve
         this.

              In  some cases, you may find that a major host
         going down for a couple of days may create  a  pro-
         hibitively  large queue.  This will result in send-
         mail spending an inordinate amount of time  sorting
         the  queue.   This situation can be fixed by moving
         the queue to a temporary place and creating  a  new
         queue.   The  old  queue  can be run later when the
         offending host returns to service.












SMM:08-24          Sendmail Installation and Operation Guide


              To do this,  it  is  acceptable  to  move  the
         entire queue directory:

             cd /var/spool
             mv mqueue omqueue; mkdir mqueue; chmod 0700 mqueue

         You  should then kill the existing daemon (since it
         will still be processing in the  old  queue  direc-
         tory) and create a new daemon.

              To run the old mail queue, issue the following
         command:

             /usr/sbin/sendmail -C /etc/mail/queue.cf -q

         The -C flag specifies  an  alternate  configuration
         file queue.cf which should refer to the moved queue
         directory

             O QueueDirectory=/var/spool/omqueue

         and the -q flag says to just run every job  in  the
         queue.  You can also specify the moved queue direc-
         tory on the command line

             /usr/sbin/sendmail -oQ/var/spool/omqueue -q

         but this requires that you do not have queue groups
         in  the  configuration  file, because those are not
         subdirectories of the  moved  directory.   See  the
         section   about   "Queue   Group  Declaration"  for
         details; you most likely need a different  configu-
         ration  file  to  correctly deal with this problem.
         However, a proper  configuration  of  queue  groups
         should  avoid  filling up queue directories, so you
         shouldn't run into this problem.   If  you  have  a
         tendency  toward voyeurism, you can use the -v flag
         to watch what is going on.

              When the queue is  finally  emptied,  you  can
         remove the directory:

             rmdir /var/spool/omqueue


   2.4.  Disk Based Connection Information

           Sendmail  stores  a  large  amount of information
      about each remote system it has connected to  in  mem-
      ory.  It is possible to preserve some of this informa-
      tion on disk as well, by using the HostStatusDirectory
      option, so that it may be shared between several invo-
      cations of sendmail.  This allows mail  to  be  queued










Sendmail Installation and Operation Guide          SMM:08-25


      immediately or skipped during a queue run if there has
      been a  recent  failure  in  connecting  to  a  remote
      machine.

           Additionally  enabling  SingleThreadDelivery  has
      the added effect of single-threading mail delivery  to
      a  destination.   This  can  be  quite  helpful if the
      remote machine is running an SMTP server that is  eas-
      ily  overloaded  or  cannot  accept more than a single
      connection at a time, but can cause some  messages  to
      be  punted  to a future queue run.  It also applies to
      all hosts,  so  setting  this  because  you  have  one
      machine on site that runs some software that is easily
      overrun can cause mail to other  hosts  to  be  slowed
      down.  If this option is set, you probably want to set
      the MinQueueAge option  as  well  and  run  the  queue
      fairly  frequently;  this  way  jobs  that are skipped
      because another sendmail is talking to the  same  host
      will  be tried again quickly rather than being delayed
      for a long time.

           The disk based host information is  stored  in  a
      subdirectory    of   the   mqueue   directory   called
      .hoststat7.  Removing this directory and its subdirec-
      tories  has an effect similar to the purgestat command
      and  is  completely  safe.   However,  purgestat  only
      removes expired (Timeout.hoststatus) data.  The infor-
      mation in these directories can be  perused  with  the
      hoststat  command,  which will indicate the host name,
      the last access, and the status of  that  access.   An
      asterisk  in  the  left  most  column indicates that a
      sendmail process currently has  the  host  locked  for
      mail delivery.

           The  disk based connection information is treated
      the same way as memory  based  connection  information
      for  the purpose of timeouts.  By default, information
      about host failures is valid for 30 minutes.  This can
      be adjusted with the Timeout.hoststatus option.

           The  connection information stored on disk may be
      expired at any time with the purgestat command  or  by
      invoking sendmail with the -bH switch.  The connection
      information may be viewed with the hoststat command or
      by invoking sendmail with the -bh switch.


____________________
   7This is the usual value of the  HostStatusDirectory  op-
tion;  it  can,  of  course,  go  anywhere  you like in your
filesystem.












SMM:08-26          Sendmail Installation and Operation Guide


   2.5.  The Service Switch

           The  implementation  of  certain  system services
      such as host and user name lookup is controlled by the
      service switch.  If the host operating system supports
      such a switch, and sendmail knows about  it,  sendmail
      will use the native version.  Ultrix, Solaris, and DEC
      OSF/1 are examples of such systems8.

           If the underlying operating system does not  sup-
      port  a  service  switch (e.g., SunOS 4.X, HP-UX, BSD)
      then sendmail will provide a stub implementation.  The
      ServiceSwitchFile  option points to the name of a file
      that has the service definitions.  Each line  has  the
      name  of a service and the possible implementations of
      that service.  For example, the file:

          hosts     dns files nis
          aliases   files nis

      will ask sendmail to look for hosts in the Domain Name
      System  first.   If  the  requested  host  name is not
      found, it tries local files,  and  if  that  fails  it
      tries  NIS.   Similarly,  when  looking for aliases it
      will try the local files first followed by NIS.

           Notice: since sendmail must access MX records for
      correct operation, it will use DNS if it is configured
      in the ServiceSwitchFile file.  Hence an entry like

          hosts     files dns

      will not avoid DNS lookups even if a host can be found
      in /etc/hosts.

           Service  switches  are not completely integrated.
      For example, despite the  fact  that  the  host  entry
      listed  in the above example specifies to look in NIS,
      on SunOS this won't happen because the  system  imple-
      mentation of gethostbyname(3) doesn't understand this.

   2.6.  The Alias Database

           After recipient addresses are read from the  SMTP
      connection  or command line they are parsed by ruleset
      0, which must resolve to  a  {mailer,  host,  address}
      triple.   If  the flags selected by the mailer include
____________________
   8HP-UX 10 has service switch support, but since the  APIs
are  apparently not available in the libraries sendmail does
not use the native service switch in this release.












Sendmail Installation and Operation Guide          SMM:08-27


      the A (aliasable) flag, the address part of the triple
      is  looked  up  as  the key (i.e., the left hand side)
      into the alias database.  If there  is  a  match,  the
      address  is  deleted  from  the  send  queue  and  all
      addresses on the right hand  side  of  the  alias  are
      added in place of the alias that was found.  This is a
      recursive operation, so aliases  found  in  the  right
      hand side of the alias are similarly expanded.

           The alias database exists in two forms.  One is a
      text form, maintained in the  file  /etc/mail/aliases.
      The aliases are of the form

          name: name1, name2, ...

      Only local names may be aliased; e.g.,

          eric@prep.ai.MIT.EDU: eric@CS.Berkeley.EDU

      will   not   have   the   desired  effect  (except  on
      prep.ai.MIT.EDU, and they probably  don't  want  me)9.
      Aliases  may be continued by starting any continuation
      lines with a space or a tab or by putting a  backslash
      directly  before  the  newline.  Blank lines and lines
      beginning with a sharp sign ("#") are comments.

           The second form is processed by the ndbm(3)10  or
      the  Berkeley  DB  library.   This form is in the file
      /etc/mail/aliases.db    (if    using     NEWDB)     or
      /etc/mail/aliases.dir  and  /etc/mail/aliases.pag  (if
      using NDBM).  This is the form that sendmail  actually
      uses  to  resolve  aliases.  This technique is used to
      improve performance.

           The control of search order is  actually  set  by
      the service switch.  Essentially, the entry

          O AliasFile=switch:aliases

      is  always  added  as the first alias entry; also, the
      first alias file name without a class  (e.g.,  without
      "nis:"  on  the front) will be used as the name of the
      file for a ``files'' entry in the aliases switch.  For
      example, if the configuration file contains

          O AliasFile=/etc/mail/aliases
____________________
   9Actually, any mailer that has the `A'  mailer  flag  set
will  permit aliasing; this is normally limited to the local
mailer.
   10The gdbm package does not work.












SMM:08-28          Sendmail Installation and Operation Guide


      and the service switch contains

          aliases   nis files nisplus

      then  aliases  will  first  be  searched  in  the  NIS
      database, then in /etc/mail/aliases, then in the  NIS+
      database.

           You  can  also  use  NIS-based  alias files.  For
      example, the specification:

          O AliasFile=/etc/mail/aliases
          O AliasFile=nis:mail.aliases@my.nis.domain

      will first search the /etc/mail/aliases file and  then
      the   map  named  "mail.aliases"  in  "my.nis.domain".
      Warning: if you build your own NIS-based alias  files,
      be  sure  to  provide the -l flag to makedbm(8) to map
      upper case letters in the keys to lower  case;  other-
      wise,  aliases  with upper case letters in their names
      won't match incoming addresses.

           Additional flags can be  added  after  the  colon
      exactly like a K line -- for example:

          O AliasFile=nis:-N mail.aliases@my.nis.domain

      will search the appropriate NIS map and always include
      null bytes in the key.  Also:

          O AliasFile=nis:-f mail.aliases@my.nis.domain

      will prevent sendmail from downcasing the  key  before
      the alias lookup.

      2.6.1.  Rebuilding the alias database

              The hash or dbm version of the database may be
         rebuilt explicitly by executing the command

             newaliases

         This is equivalent to giving sendmail the -bi flag:

             /usr/sbin/sendmail -bi


              If  you have multiple aliases databases speci-
         fied, the -bi flag rebuilds all the database  types
         it  understands  (for  example, it can rebuild NDBM
         databases but not NIS databases).












Sendmail Installation and Operation Guide          SMM:08-29


      2.6.2.  Potential problems

              There are a number of problems that can  occur
         with  the  alias  database.  They all result from a
         sendmail process accessing the DBM version while it
         is only partially built.  This can happen under two
         circumstances: One process  accesses  the  database
         while another process is rebuilding it, or the pro-
         cess rebuilding the database  dies  (due  to  being
         killed  or  a  system  crash) before completing the
         rebuild.

              Sendmail  has  three  techniques  to  try   to
         relieve  these  problems.  First, it ignores inter-
         rupts while rebuilding the  database;  this  avoids
         the problem of someone aborting the process leaving
         a partially rebuilt database.  Second, it locks the
         database source file during the rebuild -- but that
         may not work over NFS or if the file is unwritable.
         Third,  at  the end of the rebuild it adds an alias
         of the form

             @: @

         (which is not  normally  legal).   Before  sendmail
         will  access the database, it checks to insure that
         this entry exists11.

      2.6.3.  List owners

              If an error occurs on  sending  to  a  certain
         address,  say  "x", sendmail will look for an alias
         of the form "owner-x" to receive the errors.   This
         is  typically  useful  for a mailing list where the
         submitter of the list has no control over the main-
         tenance  of  the list itself; in this case the list
         maintainer would be the owner  of  the  list.   For
         example:

             unix-wizards: eric@ucbarpa, wnj@monet, nosuchuser,
                  sam@matisse
             owner-unix-wizards: unix-wizards-request
             unix-wizards-request: eric@ucbarpa

         would  cause  "eric@ucbarpa"  to get the error that
         will occur when someone sends to  unix-wizards  due
         to the inclusion of "nosuchuser" on the list.
____________________
   11The AliasWait option is required in  the  configuration
for  this  action  to occur.  This should normally be speci-
fied.












SMM:08-30          Sendmail Installation and Operation Guide


              List  owners  also  cause  the envelope sender
         address to be modified.  The contents of the  owner
         alias are used if they point to a single user, oth-
         erwise the name of the alias itself is  used.   For
         this  reason, and to obey Internet conventions, the
         "owner-" address normally points at the  "-request"
         address;  this  causes  messages to go out with the
         typical  Internet  convention  of   using   ``list-
         request'' as the return address.

   2.7.  User Information Database

           This  option is deprecated, use virtusertable and
      genericstable instead as explained in  cf/README.   If
      you  have a version of sendmail with the user informa-
      tion database compiled in, and you have specified  one
      or  more  databases  using the U option, the databases
      will be searched for a user:maildrop entry.  If found,
      the mail will be sent to the specified address.

   2.8.  Per-User Forwarding (.forward Files)

           As an alternative to the alias database, any user
      may put a file with the name ".forward" in his or  her
      home  directory.   If this file exists, sendmail redi-
      rects mail for that user  to  the  list  of  addresses
      listed  in  the  .forward file.  Note that aliases are
      fully expanded before forward  files  are  referenced.
      For example, if the home directory for user "mckusick"
      has a .forward file with contents:

          mckusick@ernie
          kirk@calder

      then any mail arriving for "mckusick"  will  be  redi-
      rected to the specified accounts.

           Actually,   the   configuration  file  defines  a
      sequence of filenames to check.  By default,  this  is
      the  user's  .forward  file,  but can be defined to be
      more generally using the ForwardPath option.   If  you
      change this, you will have to inform your user base of
      the change; .forward is pretty well incorporated  into
      the collective subconscious.

   2.9.  Special Header Lines

           Several header lines have special interpretations
      defined by the configuration file.  Others have inter-
      pretations  built into sendmail that cannot be changed
      without  changing  the  code.   These  built-ins   are
      described here.











Sendmail Installation and Operation Guide          SMM:08-31


      2.9.1.  Errors-To:

              If  errors  occur  anywhere during processing,
         this header will cause error messages to go to  the
         listed  addresses.   This  is  intended for mailing
         lists.

              The Errors-To: header was created in  the  bad
         old  days  when UUCP didn't understand the distinc-
         tion between an envelope and a header; this  was  a
         hack  to  provide  what should now be passed as the
         envelope sender address.  It should go away.  It is
         only used if the UseErrorsTo option is set.

              The Errors-To: header is officially deprecated
         and will go away in a future release.

      2.9.2.  Apparently-To:

              RFC 822 requires at least one recipient  field
         (To:,  Cc:,  or  Bcc: line) in every message.  If a
         message comes in with no recipients listed  in  the
         message  then sendmail will adjust the header based
         on the "NoRecipientAction" option.  One of the pos-
         sible  actions is to add an "Apparently-To:" header
         line for any recipients it is aware of.

              The Apparently-To: header is non-standard  and
         is both deprecated and strongly discouraged.

      2.9.3.  Precedence

              The  Precedence: header can be used as a crude
         control of message priority.  It  tweaks  the  sort
         order  in the queue and can be configured to change
         the message timeout values.  The  precedence  of  a
         message also controls how delivery status notifica-
         tions (DSNs) are processed for that message.

   2.10.  IDENT Protocol Support

           Sendmail supports the IDENT protocol  as  defined
      in RFC 1413.  Note that the RFC states a client should
      wait at least 30 seconds for a response.  The  default
      Timeout.ident  is 5 seconds as many sites have adopted
      the practice of dropping IDENT queries.  This has lead
      to  delays  processing  mail.   Although this enhances
      identification of the author of an  email  message  by
      doing  a  ``call  back''  to the originating system to
      include the owner of a particular  TCP  connection  in
      the  audit  trail  it is in no sense perfect; a deter-
      mined forger can easily spoof the IDENT protocol.  The
      following description is excerpted from RFC 1413:










SMM:08-32          Sendmail Installation and Operation Guide


           6.  Security Considerations

           The  information  returned by this protocol is at
           most as trustworthy as the host providing  it  OR
           the  organization  operating the host.  For exam-
           ple, a PC in an open lab has few if any  controls
           on it to prevent a user from having this protocol
           return any identifier the user wants.   Likewise,
           if  the host has been compromised the information
           returned may be completely erroneous and mislead-
           ing.

           The Identification Protocol is not intended as an
           authorization or  access  control  protocol.   At
           best, it provides some additional auditing infor-
           mation  with  respect  to  TCP  connections.   At
           worst,  it  can provide misleading, incorrect, or
           maliciously incorrect information.

           The use of the information returned by this  pro-
           tocol  for  other  than auditing is strongly dis-
           couraged.   Specifically,  using   Identification
           Protocol information to make access control deci-
           sions - either as the primary  method  (i.e.,  no
           other  checks)  or as an adjunct to other methods
           may result in a weakening of  normal  host  secu-
           rity.

           An  Identification  server may reveal information
           about users, entities, objects or processes which
           might normally be considered private.  An Identi-
           fication server provides service which is a rough
           analog  of the CallerID services provided by some
           phone companies and many of the same privacy con-
           siderations  and arguments that apply to the Cal-
           lerID service apply to  Identification.   If  you
           wouldn't  run  a  "finger"  server due to privacy
           considerations you may not want to run this  pro-
           tocol.

      In  some  cases your system may not work properly with
      IDENT support due to a bug in the  TCP/IP  implementa-
      tion.   The  symptoms  will be that for some hosts the
      SMTP connection will be closed almost immediately.  If
      this  is  true or if you do not want to use IDENT, you
      should set the IDENT timeout to zero; this  will  dis-
      able the IDENT protocol.

3.  ARGUMENTS

        The  complete  list  of  arguments  to  sendmail  is
   described in detail in Appendix A.  Some important  argu-
   ments are described here.










Sendmail Installation and Operation Guide          SMM:08-33


   3.1.  Queue Interval

           The  amount  of time between forking a process to
      run through the queue is defined by the -q  flag.   If
      you  run  with delivery mode set to i or b this can be
      relatively large, since it will only be relevant  when
      a  host  that was down comes back up.  If you run in q
      mode it should be relatively short, since  it  defines
      the  maximum  amount of time that a message may sit in
      the queue.  (See also the MinQueueAge option.)

           RFC 1123 section 5.3.1.1  says  that  this  value
      should  be at least 30 minutes (although that probably
      doesn't make sense if you use ``queue-only'' mode).

           Notice: the meaning of the interval time  depends
      on  whether  normal  queue runners or persistent queue
      runners are used.  For the  former,  it  is  the  time
      between  subsequent  starts  of  a queue run.  For the
      latter, it is the time sendmail waits after a  persis-
      tent  queue  runner has finished its work to start the
      next one.  Hence for  persistent  queue  runners  this
      interval  should  be  very low, typically no more than
      two minutes.

   3.2.  Daemon Mode

           If you allow incoming mail over  an  IPC  connec-
      tion,  you  should have a daemon running.  This should
      be set by your /etc/rc file using the -bd  flag.   The
      -bd flag and the -q flag may be combined in one call:

          /usr/sbin/sendmail -bd -q30m


           An  alternative  approach  is  to invoke sendmail
      from inetd(8) (use the -bs -Am flags to  ask  sendmail
      to  speak SMTP on its standard input and output and to
      run as MTA).  This works and allows you to wrap  send-
      mail in a TCP wrapper program, but may be a bit slower
      since the configuration file  has  to  be  re-read  on
      every  message  that  comes  in.   If you do this, you
      still need to have a sendmail  running  to  flush  the
      queue:

          /usr/sbin/sendmail -q30m


   3.3.  Forcing the Queue

           In  some  cases  you  may find that the queue has
      gotten clogged for some reason.  You can force a queue
      run  using  the  -q  flag  (with  no  value).   It  is










SMM:08-34          Sendmail Installation and Operation Guide


      entertaining to use the -v flag (verbose) when this is
      done to watch what happens:

          /usr/sbin/sendmail -q -v


           You  can also limit the jobs to those with a par-
      ticular queue identifier, recipient, sender, or  queue
      group  using one of the queue modifiers.  For example,
      "-qRberkeley" restricts the queue  run  to  jobs  that
      have  the  string  "berkeley"  somewhere in one of the
      recipient addresses.   Similarly,  "-qSstring"  limits
      the  run  to particular senders, "-qIstring" limits it
      to particular queue identifiers, and "-qGstring"  lim-
      its  it  to  a  particular  queue group.  You may also
      place an !  before the I or R or S  to  indicate  that
      jobs  are  limited to not including a particular queue
      identifier,  recipient  or   sender.    For   example,
      "-q!Rseattle" limits the queue run to jobs that do not
      have the string "seattle"  somewhere  in  one  of  the
      recipient addresses.  Should you need to terminate the
      queue jobs currently active then a SIGTERM to the par-
      ent  of  the  process (or processes) will cleanly stop
      the jobs.

   3.4.  Debugging

           There are a fairly large number  of  debug  flags
      built  into  sendmail.  Each debug flag has a category
      and a level.  Higher  levels  increase  the  level  of
      debugging activity; in most cases, this means to print
      out more information.  The convention is  that  levels
      greater  than  nine are "absurd," i.e., they print out
      so much information that you wouldn't normally want to
      see them except for debugging that particular piece of
      code.

           A debug category is either an integer,  like  42,
      or  a  name,  like  ANSI.   You can specify a range of
      numeric debug categories using the syntax 17-42.   You
      can  specify  a  set of named debug categories using a
      glob pattern like "sm_trace_*".  At present, only  "*"
      and "?"  are supported in these glob patterns.

           Debug flags are set using the -d option; the syn-
      tax is:

          debug-flag:        -d debug-list
          debug-list:        debug-option [ , debug-option ]*
          debug-option:      debug-categories [ . debug-level ]
          debug-categories:  integer | integer - integer | category-pattern
          category-pattern:  [a-zA-Z_*?][a-zA-Z0-9_*?]*
          debug-level:       integer










Sendmail Installation and Operation Guide          SMM:08-35


      where spaces are for reading ease only.  For example,

          -d12               Set category 12 to level 1
          -d12.3             Set category 12 to level 3
          -d3-17             Set categories 3 through 17 to level 1
          -d3-17.4           Set categories 3 through 17 to level 4
          -dANSI             Set category ANSI to level 1
          -dsm_trace_*.3     Set all named categories matching sm_trace_* to level 3

      For a complete list of the available debug  flags  you
      will  have to look at the code and the TRACEFLAGS file
      in the sendmail distribution (they are too dynamic  to
      keep  this  document up to date).  For a list of named
      debug categories in the sendmail binary, use

          ident /usr/sbin/sendmail | grep Debug


   3.5.  Changing the Values of Options

           Options can be overridden using the -o or -O com-
      mand line flags.  For example,

          /usr/sbin/sendmail -oT2m

      sets  the  T  (timeout) option to two minutes for this
      run only; the equivalent line using  the  long  option
      name is

          /usr/sbin/sendmail -OTimeout.queuereturn=2m


           Some  options  have security implications.  Send-
      mail allows you to set  these,  but  relinquishes  its
      set-user-ID or set-group-ID permissions  thereafter12.

   3.6.  Trying a Different Configuration File

           An  alternative  configuration file can be speci-
      fied using the -C flag; for example,

          /usr/sbin/sendmail -Ctest.cf -oQ/tmp/mqueue

      uses the configuration file  test.cf  instead  of  the
      default  /etc/mail/sendmail.cf.  If the -C flag has no
      value  it  defaults  to  sendmail.cf  in  the  current
____________________
   12That  is,  it  sets  its effective uid to the real uid;
thus, if you are executing as root, as from  root's  crontab
file  or  during  system  startup  the root permissions will
still be honored.












SMM:08-36          Sendmail Installation and Operation Guide


      directory.

           Sendmail  gives  up  set-user-ID root permissions
      (if it has been installed set-user-ID root)  when  you
      use  this  flag,  so  it  is  common to use a publicly
      writable directory (such as /tmp) as the queue  direc-
      tory (QueueDirectory or Q option) while testing.

   3.7.  Logging Traffic

           Many  SMTP implementations do not fully implement
      the protocol.  For  example,  some  personal  computer
      based  SMTPs  do  not understand continuation lines in
      reply codes.  These can be very hard to trace.  If you
      suspect  such  a  problem, you can set traffic logging
      using the -X flag.  For example,

          /usr/sbin/sendmail -X /tmp/traffic -bd

      will log all traffic in the file /tmp/traffic.

           This logs a lot of data very quickly  and  should
      NEVER  be used during normal operations.  After start-
      ing up such a daemon, force the errant  implementation
      to  send  a message to your host.  All message traffic
      in and out of sendmail, including  the  incoming  SMTP
      traffic, will be logged in this file.

   3.8.  Testing Configuration Files

           When  you build a configuration table, you can do
      a certain amount of testing using the "test  mode"  of
      sendmail.  For example, you could invoke sendmail as:

          sendmail -bt -Ctest.cf

      which  would read the configuration file "test.cf" and
      enter test mode.  In this mode, you enter lines of the
      form:

          rwset address

      where  rwset  is the rewriting set you want to use and
      address is an address to apply the set to.  Test  mode
      shows  you  the steps it takes as it proceeds, finally
      showing you the address it ends up with.  You may  use
      a comma separated list of rwsets for sequential appli-
      cation of rules to an input.  For example:

          3,1,21,4 monet:bollard

      first applies ruleset three to the  input  "monet:bol-
      lard."   Ruleset  one is then applied to the output of










Sendmail Installation and Operation Guide          SMM:08-37


      ruleset three, followed similarly by rulesets  twenty-
      one and four.

           If  you  need  more  detail, you can also use the
      "-d21" flag to turn on more debugging.  For example,

          sendmail -bt -d21.99

      turns on an incredible amount of information; a single
      word  address  is  probably going to print out several
      pages worth of information.

           You should be warned  that  internally,  sendmail
      applies  ruleset 3 to all addresses.  In test mode you
      will have to do that  manually.   For  example,  older
      versions allowed you to use

          0 bruce@broadcast.sony.com

      This version requires that you use:

          3,0 bruce@broadcast.sony.com


           As of version 8.7, some other syntaxes are avail-
      able in test mode:

      .Dxvalue  defines macro x to have the indicated value.
                This is useful when debugging rules that use
                the $&x syntax.

      .Ccvalue  adds the indicated value to class c.

      =Sruleset dumps the contents of the indicated ruleset.

      -ddebug-spec
                is equivalent to the command-line flag.

      Version 8.9 introduced more features:

      ?         shows a help message.

      =M        display the known mailers.

      $m        print the value of macro m.

      $=c       print the contents of class c.

      /mx host  returns the MX records for `host'.

      /parse address
                parse address, returning the value of crack-
                addr, and the parsed address.










SMM:08-38          Sendmail Installation and Operation Guide


      /try mailer addr
                rewrite address into the form it  will  have
                when presented to the indicated mailer.

      /tryflags flags
                set flags used by parsing.  The flags can be
                `H' for Header or `E' for Envelope, and  `S'
                for  Sender or `R' for Recipient.  These can
                be combined,  `HR'  sets  flags  for  header
                recipients.

      /canon hostname
                try to canonify hostname.

      /map mapname key
                look up `key' in the indicated `mapname'.

      /quit     quit address test mode.

   3.9.  Persistent Host Status Information

           When  HostStatusDirectory is enabled, information
      about the status of hosts is maintained  on  disk  and
      can thus be shared between different instantiations of
      sendmail.  The status of the last connection with each
      remote host may be viewed with the command:

          sendmail -bh

      This information may be flushed with the command:

          sendmail -bH

      Flushing  the  information  prevents new sendmail pro-
      cesses from loading it, but does not prevent  existing
      processes  from using the status information that they
      already have.

4.  TUNING

        There are a number of configuration  parameters  you
   may want to change, depending on the requirements of your
   site.  Most of these are set using an option in the  con-
   figuration   file.    For  example,  the  line  "O  Time-
   out.queuereturn=5d" sets option "Timeout.queuereturn"  to
   the value "5d" (five days).

        Most  of these options have appropriate defaults for
   most sites.  However, sites having very high  mail  loads
   may  find they need to tune them as appropriate for their
   mail load.  In particular,  sites  experiencing  a  large
   number  of small messages, many of which are delivered to
   many recipients, may find that they need  to  adjust  the










Sendmail Installation and Operation Guide          SMM:08-39


   parameters dealing with queue priorities.

        All  versions  of  sendmail  prior to 8.7 had single
   character option names.  As of  8.7,  options  have  long
   (multi-character  names).   Although  old short names are
   still accepted, most new options do not have short equiv-
   alents.

        This section only describes the options you are most
   likely to want to tweak; read section 5 for more details.

   4.1.  Timeouts

           All time intervals are set using a scaled syntax.
      For example, "10m"  represents  ten  minutes,  whereas
      "2h30m" represents two and a half hours.  The full set
      of scales is:

          s   seconds
          m   minutes
          h   hours
          d   days
          w   weeks


      4.1.1.  Queue interval

              The argument to  the  -q  flag  specifies  how
         often  a  sub-daemon  will  run the queue.  This is
         typically set to between fifteen  minutes  and  one
         hour.   If  not set, or set to zero, the queue will
         not be run automatically.  RFC 1123 section 5.3.1.1
         recommends  that  this  be  at  least  30  minutes.
         Should you need to terminate the  queue  jobs  cur-
         rently  active  then a SIGTERM to the parent of the
         process (or processes) will cleanly stop the  jobs.

      4.1.2.  Read timeouts

              Timeouts all have option names "Timeout.subop-
         tion".  Most of these control SMTP operations.  The
         recognized  suboptions,  their  default values, and
         the minimum values  allowed  by  RFC  2821  section
         4.5.3.2 (or RFC 1123 section 5.3.2) are:

         connect   The  time  to wait for an SMTP connection
                   to open (the connect(2) system call)  [0,
                   unspecified].   If  zero, uses the kernel
                   default.  In  no  case  can  this  option
                   extend the timeout longer than the kernel
                   provides, but it can shorten it.  This is
                   to  get  around  kernels  that provide an
                   absurdly  long  connection  timeout   (90










SMM:08-40          Sendmail Installation and Operation Guide


                   minutes in one case).

         iconnect  The  same  as  connect, except it applies
                   only to the initial attempt to connect to
                   a  host  for a given message [0, unspeci-
                   fied].  The concept is that  this  should
                   be very short (a few seconds); hosts that
                   are well connected  and  responsive  will
                   thus be serviced immediately.  Hosts that
                   are slow will not hold up other  deliver-
                   ies in the initial delivery attempt.

         aconnect  [0,   unspecified]  The  overall  timeout
                   waiting for all connection for  a  single
                   delivery  attempt  to  succeed.  If 0, no
                   overall limit is applied.   This  can  be
                   used to restrict the total amount of time
                   trying to connect to a long list of  host
                   that  could  accept  an  e-mail  for  the
                   recipient.  This timeout does  not  apply
                   to  FallbackMXhost,  i.e., if the time is
                   exhausted, the  FallbackMXhost  is  tried
                   next.

         initial   The  wait  for  the  initial 220 greeting
                   message [5m, 5m].

         helo      The wait for a reply from a HELO or  EHLO
                   command   [5m,  unspecified].   This  may
                   require a host name lookup, so five  min-
                   utes is probably a reasonable minimum.

         mail*     The  wait for a reply from a MAIL command
                   [10m, 5m].

         rcpt*     The wait for a reply from a RCPT  command
                   [1h, 5m].  This should be long because it
                   could be pointing at a list that takes  a
                   long time to expand (see below).

         datainit* The  wait for a reply from a DATA command
                   [5m, 2m].

         datablock*#
                   The wait for reading a data  block  (that
                   is,  the body of the message).  [1h, 3m].
                   This  should  be  long  because  it  also
                   applies to programs piping input to send-
                   mail which have no guarantee  of  prompt-
                   ness.

         datafinal*
                   The   wait  for  a  reply  from  the  dot










Sendmail Installation and Operation Guide          SMM:08-41


                   terminating a message.   [1h,  10m].   If
                   this  is  shorter  than the time actually
                   needed for the receiver  to  deliver  the
                   message,  duplicates  will  be generated.
                   This is discussed in RFC 1047.

         rset      The wait for a reply from a RSET  command
                   [5m, unspecified].

         quit      The  wait for a reply from a QUIT command
                   [2m, unspecified].

         misc      The wait for a reply  from  miscellaneous
                   (but  short)  commands  such as NOOP (no-
                   operation)  and  VERB  (go  into  verbose
                   mode).  [2m, unspecified].

         command*# In  server  SMTP,  the  time  to wait for
                   another command.  [1h, 5m].

         ident#    The timeout waiting for  a  reply  to  an
                   IDENT query [5s13, unspecified].

         lhlo      The wait for a reply to an LMTP LHLO com-
                   mand [2m, unspecified].

         auth      The  timeout  for a reply in an SMTP AUTH
                   dialogue [10m, unspecified].

         starttls  The timeout for a reply to an SMTP START-
                   TLS  command  and  the TLS handshake [1h,
                   unspecified].

         fileopen# The  timeout  for  opening  .forward  and
                   :include: files [60s, none].

         control#  The timeout for a complete control socket
                   transaction to complete [2m, none].

         hoststatus#
                   How long status information about a  host
                   (e.g.,  host  down) will be cached before
                   it is  considered  stale  [30m,  unspeci-
                   fied].

         resolver.retrans#
                   The resolver's retransmission time inter-
                   val (in  seconds)  [varies].   Sets  both
____________________
   13On  some systems the default is zero to turn the proto-
col off entirely.












SMM:08-42          Sendmail Installation and Operation Guide


                   Timeout.resolver.retrans.first  and Time-
                   out.resolver.retrans.normal.

         resolver.retrans.first#
                   The resolver's retransmission time inter-
                   val (in seconds) for the first attempt to
                   deliver a message [varies].

         resolver.retrans.normal#
                   The resolver's retransmission time inter-
                   val (in seconds) for all resolver lookups
                   except   the   first   delivery   attempt
                   [varies].

         resolver.retry#
                   The  number  of  times  to  retransmit  a
                   resolver   query.    Sets   both    Time-
                   out.resolver.retry.first     and    Time-
                   out.resolver.retry.normal [varies].

         resolver.retry.first#
                   The  number  of  times  to  retransmit  a
                   resolver  query  for the first attempt to
                   deliver a message [varies].

         resolver.retry.normal#
                   The  number  of  times  to  retransmit  a
                   resolver query for all resolver lookups
                    except   the   first   delivery  attempt
                   [varies].

         For compatibility with old configuration files,  if
         no  suboption is specified, all the timeouts marked
         with an asterick  (*)  are  set  to  the  indicated
         value.   All but those marked with a pound sign (#)
         apply to client SMTP.

              For example, the lines:

             O Timeout.command=25m
             O Timeout.datablock=3h

         sets the server SMTP command timeout to 25  minutes
         and the input data block timeout to three hours.

      4.1.3.  Message timeouts

              After  sitting in the queue for a few days, an
         undeliverable message will time out.   This  is  to
         insure  that  at  least  the sender is aware of the
         inability to send a message.  The timeout is  typi-
         cally set to five days.  It is sometimes considered
         convenient to also send a warning  message  if  the










Sendmail Installation and Operation Guide          SMM:08-43


         message  is  in  the  queue longer than a few hours
         (assuming you normally have good  connectivity;  if
         your  messages  normally took several hours to send
         you wouldn't want to do this because it wouldn't be
         an  unusual  event).   These timeouts are set using
         the   Timeout.queuereturn   and   Timeout.queuewarn
         options  in the configuration file (previously both
         were set using the T option).

              If the message is submitted using  the  NOTIFY
         SMTP  extension, warning messages will only be sent
         if NOTIFY=DELAY is specified.  The queuereturn  and
         queuewarn  timeouts can be further qualified with a
         tag based on the Precedence: field in the  message;
         they must be one of "urgent" (indicating a positive
         non-zero precedence) "normal"  (indicating  a  zero
         precedence),  or  "non-urgent" (indicating negative
         precedences).  For example, setting "Timeout.queue-
         warn.urgent=1h" sets the warning timeout for urgent
         messages only to  one  hour.   The  default  if  no
         precedence  is  indicated is to set the timeout for
         all precedences.  The value "now" can be  used  for
         -O  Timeout.queuereturn  to  return entries immedi-
         ately during a queue run, e.g., to bounce  messages
         independent of their time in the queue.

              Since  these options are global, and since you
         cannot know a priori how long another host  outside
         your  domain  will  be  down, a five day timeout is
         recommended.  This allows a recipient  to  fix  the
         problem  even  if  it  occurs at the beginning of a
         long weekend.  RFC 1123 section 5.3.1.1  says  that
         this parameter should be ``at least 4-5 days''.

              The Timeout.queuewarn value can be piggybacked
         on the T option by indicating a time after which  a
         warning  message  should  be sent; the two timeouts
         are separated by a slash.  For example, the line

             OT5d/4h

         causes email to fail after five days, but a warning
         message will be sent after four hours.  This should
         be large enough that the  message  will  have  been
         tried several times.

   4.2.  Forking During Queue Runs

           By  setting  the ForkEachJob (Y) option, sendmail
      will fork before each individual message while running
      the queue.  This option was used with earlier releases
      to prevent sendmail from consuming  large  amounts  of
      memory.    It  should  no  longer  be  necessary  with










SMM:08-44          Sendmail Installation and Operation Guide


      sendmail 8.12.  If the ForkEachJob option is not  set,
      sendmail will keep track of hosts that are down during
      a queue run, which can  improve  performance  dramati-
      cally.

           If the ForkEachJob option is set, sendmail cannot
      use connection caching.

   4.3.  Queue Priorities

           Every message is assigned a priority when  it  is
      first instantiated, consisting of the message size (in
      bytes) offset by the message class  (which  is  deter-
      mined  from  the  Precedence:  header) times the "work
      class factor" and the number of recipients  times  the
      "work  recipient  factor."   The  priority  is used to
      order the queue.  Higher numbers for the priority mean
      that  the message will be processed later when running
      the queue.

           The message size is included so that  large  mes-
      sages  are  penalized relative to small messages.  The
      message class allows users  to  send  "high  priority"
      messages  by  including a "Precedence:" field in their
      message; the value of this field is looked up in the P
      lines  of the configuration file.  Since the number of
      recipients  affects  the  amount  of  load  a  message
      presents to the system, this is also included into the
      priority.

           The recipient and class factors can be set in the
      configuration  file  using the RecipientFactor (y) and
      ClassFactor (z) options respectively.  They default to
      30000  (for  the  recipient  factor) and 1800 (for the
      class factor).  The initial priority is:

     pri=msgsize-(classxClassFactor)+(nrcptxRecipientFactor)

      (Remember, higher values for this  parameter  actually
      mean  that  the  job will be treated with lower prior-
      ity.)

           The priority of a job can also be  adjusted  each
      time it is processed (that is, each time an attempt is
      made to deliver it) using the "work time factor,"  set
      by  the  RetryFactor (Z) option.  This is added to the
      priority, so it normally decreases the  precedence  of
      the  job,  on  the  grounds that jobs that have failed
      many times will tend to fail again in the future.  The
      RetryFactor option defaults to 90000.













Sendmail Installation and Operation Guide          SMM:08-45


   4.4.  Load Limiting

           Sendmail  can be asked to queue (but not deliver)
      mail if the system load average gets  too  high  using
      the QueueLA (x) option.  When the load average exceeds
      the value of the QueueLA option, the delivery mode  is
      set  to  q  (queue only) if the QueueFactor (q) option
      divided by the difference in the current load  average
      and  the QueueLA option plus one is less than the pri-
      ority of the message -- that is, the message is queued
      iff:

                        pri>LQueueFactor_

      The  QueueFactor  option  defaults  to 600000, so each
      point of load average is worth 600000 priority  points
      (as described above).

           For   drastic  cases,  the  RefuseLA  (X)  option
      defines a load average at which sendmail  will  refuse
      to  accept  network  connections.   Locally  generated
      mail, i.e., mail  which  is  not  submitted  via  SMTP
      (including  incoming  UUCP  mail),  is still accepted.
      Notice that the MSP submits mail to the MTA via  SMTP,
      and  hence  mail will be queued in the client queue in
      such a case.  Therefore it is  necessary  to  run  the
      client mail queue periodically.

   4.5.  Resource Limits

           Sendmail   has   several  parameters  to  control
      resource usage.  Besides those mentionted in the  pre-
      vious  section,  there are at least MaxDaemonChildren,
      ConnectionRateThrottle, MaxQueueChildren, and  MaxRun-
      nersPerQueue.   The  latter  two  limit  the number of
      sendmail processes that operate on the  queue.   These
      are  discussed  in  the section ``Queue Group Declara-
      tion''.  The former two can be used to limit the  num-
      ber of incoming connections.  Their appropriate values
      depend on the host operating system and the  hardware,
      e.g.,  amount  of memory.  In many situations it might
      be useful to set limits to prevent to  have  too  many
      sendmail  processes,  however,  these  limits  can  be
      abused to mount a denial of service attack.  For exam-
      ple, if MaxDaemonChildren=10 then an attacker needs to
      open only 10 SMTP sessions to the server,  leave  them
      idle  for  most  of  the time, and no more connections
      will be accepted.

   4.6.  Delivery Mode

           There are a number of delivery modes  that  send-
      mail  can  operate  in,  set  by  the DeliveryMode (d)










SMM:08-46          Sendmail Installation and Operation Guide


      configuration option.  These modes specify how quickly
      mail will be delivered.  Legal modes are:

          i   deliver interactively (synchronously)
          b   deliver in background (asynchronously)
          q   queue only (don't deliver)
          d   defer delivery attempts (don't deliver)

      There  are  tradeoffs.   Mode "i" gives the sender the
      quickest feedback, but may slow down some mailers  and
      is  hardly ever necessary.  Mode "b" delivers promptly
      but can cause large numbers of processes if you have a
      mailer  that  takes  a long time to deliver a message.
      Mode "q" minimizes the load on your machine, but means
      that  delivery  may  be  delayed  for  up to the queue
      interval.  Mode "d" is identical to  mode  "q"  except
      that it also prevents lookups in maps including the -D
      flag from working during the initial queue  phase;  it
      is  intended  for  ``dial  on demand'' sites where DNS
      lookups might cost real money.  Some simple error mes-
      sages  (e.g.,  host  unknown during the SMTP protocol)
      will be delayed using this  mode.   Mode  "b"  is  the
      usual default.

           If you run in mode "q" (queue only), "d" (defer),
      or "b"  (deliver  in  background)  sendmail  will  not
      expand  aliases and follow .forward files upon initial
      receipt of the mail.  This speeds up the  response  to
      RCPT  commands.   Mode  "i"  should not be used by the
      SMTP server.

   4.7.  Log Level

           The level of logging can  be  set  for  sendmail.
      The  default  using  a standard configuration table is
      level 9.  The levels are as follows:

      0    Minimal logging.

      1    Serious system failures  and  potential  security
           problems.

      2    Lost communications (network problems) and proto-
           col failures.

      3    Other  serious  failures,  malformed   addresses,
           transient   forward/include   errors,  connection
           timeouts.

      4    Minor failures, out of date alias databases, con-
           nection rejections via check_ rulesets.












Sendmail Installation and Operation Guide          SMM:08-47


      5    Message collection statistics.

      6    Creation  of  error  messages, VRFY and EXPN com-
           mands.

      7    Delivery failures (host or user unknown, etc.).

      8    Successful   deliveries   and   alias    database
           rebuilds.

      9    Messages  being  deferred  (due  to  a host being
           down, etc.).

      10   Database expansion (alias,  forward,  and  userdb
           lookups) and authentication information.

      11   NIS errors and end of job processing.

      12   Logs all SMTP connections.

      13   Log  bad user shells, files with improper permis-
           sions, and other questionable situations.

      14   Logs refused connections.

      15   Log all incoming and outgoing SMTP commands.

      20   Logs attempts to run locked queue  files.   These
           are not errors, but can be useful to note if your
           queue appears to be clogged.

      30   Lost  locks  (only  if  using  lockf  instead  of
           flock).

      Additionally,   values   above  64  are  reserved  for
      extremely verbose debugging output.   No  normal  site
      would ever set these.

   4.8.  File Modes

           The modes used for files depend on what function-
      ality you want and the level of security you  require.
      In  many  cases  sendmail does careful checking of the
      modes of files and  directories  to  avoid  accidental
      compromise;  if  you  want to make it possible to have
      group-writable support files you may need to  use  the
      DontBlameSendmail  option  to  turn  off some of these
      checks.

      4.8.1.  To suid or not to suid?

              Sendmail is no longer installed set-user-ID to
         root.   sendmail/SECURITY explains how to configure










SMM:08-48          Sendmail Installation and Operation Guide


         and install sendmail without  set-user-ID  to  root
         but set-group-ID which is the default configuration
         starting with 8.12.

              The daemon usually runs as root, unless  other
         measures are taken.  At the point where sendmail is
         about to exec(2) a mailer, it checks to see if  the
         userid  is zero (root); if so, it resets the userid
         and groupid to a default (set by the U=  equate  in
         the  mailer  line; if that is not set, the Default-
         User option is used).  This can  be  overridden  by
         setting  the  S flag to the mailer for mailers that
         are trusted and must be called as  root.   However,
         this  will  cause  mail  processing to be accounted
         (using sa(8)) to root rather than to the user send-
         ing the mail.

              A  middle  ground  is  to  set  the  RunAsUser
         option.  This causes sendmail to become  the  indi-
         cated  user as soon as it has done the startup that
         requires root privileges  (primarily,  opening  the
         SMTP  socket).   If  you  use  RunAsUser, the queue
         directory (normally  /var/spool/mqueue)  should  be
         owned  by  that  user,  and all files and databases
         (including  user  .forward  files,   alias   files,
         :include:  files,  and  external databases) must be
         readable by that user.  Also, since  sendmail  will
         not  be  able  to change it's uid, delivery to pro-
         grams or files will  be  marked  as  unsafe,  e.g.,
         undeliverable,  in .forward, aliases, and :include:
         files.  Administrators can override this by setting
         the  DontBlameSendmail  option  to the setting Non-
         RootSafeAddr.  RunAsUser is  probably  best  suited
         for firewall configurations that don't have regular
         user logins.

      4.8.2.  Turning off security checks

              Sendmail is very particular about the modes of
         files  that  it  reads  or writes.  For example, by
         default it will refuse to read most files that  are
         group  writable on the grounds that they might have
         been tampered with by someone other than the owner;
         it will even refuse to read files in group writable
         directories.  Also, sendmail will refuse to  create
         a new aliases database in an unsafe directory.  You
         can  get  around  this  by  manually  creating  the
         database  file  as a trusted user ahead of time and
         then   rebuilding   the   aliases   database   with
         newaliases.

              If  you are quite sure that your configuration
         is safe  and  you  want  sendmail  to  avoid  these










Sendmail Installation and Operation Guide          SMM:08-49


         security  checks,  you  can turn off certain checks
         using the DontBlameSendmail  option.   This  option
         takes  one  or  more names that disable checks.  In
         the descriptions that  follow,  "unsafe  directory"
         means  a directory that is writable by anyone other
         than the owner.  The values are:

         Safe No special handling.

         AssumeSafeChown
              Assume  that  the   chown   system   call   is
              restricted  to  root.   Since some versions of
              UNIX permit regular users to give  away  their
              files  to  other  users  on  some filesystems,
              sendmail often cannot assume that a given file
              was created by the owner, particularly when it
              is in a writable directory.  You can set  this
              flag   if  you  know  that  file  giveaway  is
              restricted on your system.

         ClassFileInUnsafeDirPath
              When reading class files (using the F line  in
              the  configuration file), allow files that are
              in unsafe directories.

         DontWarnForwardFileInUnsafeDirPath
              Prevent logging of unsafe directory path warn-
              ings for non-existent forward files.

         ErrorHeaderInUnsafeDirPath
              Allow the file named in the ErrorHeader option
              to be in an unsafe directory.

         FileDeliveryToHardLink
              Allow delivery to files that are hard links.

         FileDeliveryToSymLink
              Allow delivery  to  files  that  are  symbolic
              links.

         ForwardFileInGroupWritableDirPath
              Allow  .forward files in group writable direc-
              tories.

         ForwardFileInUnsafeDirPath
              Allow .forward files in unsafe directories.

         ForwardFileInUnsafeDirPathSafe
              Allow a .forward file that  is  in  an  unsafe
              directory to include references to program and
              files.












SMM:08-50          Sendmail Installation and Operation Guide


         GroupReadableKeyFile
              Accept a group-readable key file for STARTTLS.

         GroupReadableSASLDBFile
              Accept  a  group-readable  Cyrus SASL password
              file.

         GroupWritableAliasFile
              Allow group-writable alias files.

         GroupWritableDirPathSafe
              Change the definition of "unsafe directory" to
              consider   group-writable  directories  to  be
              safe.  World-writable directories  are  always
              unsafe.

         GroupWritableForwardFile
              Allow group writable .forward files.

         GroupWritableForwardFileSafe
              Accept  group-writable  .forward files as safe
              for program and file delivery.

         GroupWritableIncludeFile
              Allow group wriable :include: files.

         GroupWritableIncludeFileSafe
              Accept group-writable :include: files as  safe
              for program and file delivery.

         GroupWritableSASLDBFile
              Accept  a  group-writable  Cyrus SASL password
              file.

         HelpFileInUnsafeDirPath
              Allow the file named in the HelpFile option to
              be in an unsafe directory.

         IncludeFileInGroupWritableDirPath
              Allow :include: files in group writable direc-
              tories.

         IncludeFileInUnsafeDirPath
              Allow :include: files in unsafe directories.

         IncludeFileInUnsafeDirPathSafe
              Allow a :include: file that is  in  an  unsafe
              directory to include references to program and
              files.

         InsufficientEntropy
              Try to use  STARTTLS  even  if  the  PRNG  for
              OpenSSL  is  not  properly  seeded despite the










Sendmail Installation and Operation Guide          SMM:08-51


              security problems.

         LinkedAliasFileInWritableDir
              Allow an alias  file  that  is  a  link  in  a
              writable directory.

         LinkedClassFileInWritableDir
              Allow  class  files that are links in writable
              directories.

         LinkedForwardFileInWritableDir
              Allow  .forward  files  that  are   links   in
              writable directories.

         LinkedIncludeFileInWritableDir
              Allow   :include:  files  that  are  links  in
              writable directories.

         LinkedMapInWritableDir
              Allow map files that  are  links  in  writable
              directories.   This  includes  alias  database
              files.

         LinkedServiceSwitchFileInWritableDir
              Allow the service switch file  to  be  a  link
              even if the directory is writable.

         MapInUnsafeDirPath
              Allow  maps (e.g., hash, btree, and dbm files)
              in unsafe directories.   This  includes  alias
              database files.

         NonRootSafeAddr
              Do  not  mark  file  and program deliveries as
              unsafe if sendmail is not  running  with  root
              privileges.

         RunProgramInUnsafeDirPath
              Run  programs that are in writable directories
              without logging a warning.

         RunWritableProgram
              Run programs that are group- or world-writable
              without logging a warning.

         TrustStickyBit
              Allow  group  or world writable directories if
              the sticky bit is set on  the  directory.   Do
              not set this on systems which do not honor the
              sticky bit on directories.

         WorldWritableAliasFile
              Accept world-writable alias files.










SMM:08-52          Sendmail Installation and Operation Guide


         WorldWritableForwardfile
              Allow world writable .forward files.

         WorldWritableIncludefile
              Allow world wriable :include: files.

         WriteMapToHardLink
              Allow writes to maps that are hard links.

         WriteMapToSymLink
              Allow writes to maps that are symbolic  links.

         WriteStatsToHardLink
              Allow the status file to be a hard link.

         WriteStatsToSymLink
              Allow the status file to be a symbolic link.

   4.9.  Connection Caching

           When  processing  the queue, sendmail will try to
      keep the last  few  open  connections  open  to  avoid
      startup  and shutdown costs.  This only applies to IPC
      connections.

           When trying to open a  connection  the  cache  is
      first searched.  If an open connection is found, it is
      probed to see if it is still active by sending a  RSET
      command.   It  is not an error if this fails; instead,
      the connection is closed and reopened.

           Two parameters control the connection cache.  The
      ConnectionCacheSize  (k)  option defines the number of
      simultaneous open connections that will be  permitted.
      If  it  is  set to zero, connections will be closed as
      quickly as possible.  The default is one.  This should
      be  set  as  appropriate for your system size; it will
      limit the amount of  system  resources  that  sendmail
      will  use  during  queue  runs.  Never set this higher
      than 4.

           The ConnectionCacheTimeout (K)  option  specifies
      the  maximum  time  that any cached connection will be
      permitted to idle.  When the idle  time  exceeds  this
      value the connection is closed.  This number should be
      small (under ten minutes) to prevent you from grabbing
      too  many  resources from other hosts.  The default is
      five minutes.

   4.10.  Name Server Access

           Control of host address lookups  is  set  by  the
      hosts  service  entry in your service switch file.  If










Sendmail Installation and Operation Guide          SMM:08-53


      you are on a system that has built-in  service  switch
      support  (e.g.,  Ultrix,  Solaris,  or DEC OSF/1) then
      your system is probably configured  properly  already.
      Otherwise,    sendmail    will    consult   the   file
      /etc/mail/service.switch,  which  should  be  created.
      Sendmail  only  uses  two  entries: hosts and aliases,
      although  system  routines  may  use  other   services
      (notably  the  passwd service for user name lookups by
      getpwname).

           However, some systems (such as SunOS 4.X) will do
      DNS  lookups  regardless of the setting of the service
      switch entry.  In particular, the system routine geth-
      ostbyname(3)  is  used to look up host names, and many
      vendor versions try some combination of DNS, NIS,  and
      file lookup in /etc/hosts without consulting a service
      switch.  Sendmail makes no attempt to work around this
      problem,  and  the DNS lookup will be done anyway.  If
      you do not have a nameserver configured at  all,  such
      as  at  a UUCP-only site, sendmail will get a "connec-
      tion refused" message when it tries to connect to  the
      name  server.   If the hosts switch entry has the ser-
      vice "dns" listed somewhere in the list, sendmail will
      interpret  this  to  mean a temporary failure and will
      queue the mail for  later  processing;  otherwise,  it
      ignores the name server data.

           The  same  technique is used to decide whether to
      do MX lookups.  If you want MX support, you must  have
      "dns" listed as a service in the hosts switch entry.

           The  ResolverOptions  (I)  option  allows  you to
      tweak name server options.  The command line  takes  a
      series of flags as documented in resolver(3) (with the
      leading "RES_" deleted).  Each can be preceded  by  an
      optional `+' or `-'.  For example, the line

          O ResolverOptions=+AAONLY -DNSRCH

      turns  on  the  AAONLY  (accept  authoritative answers
      only) and turns off  the  DNSRCH  (search  the  domain
      path)   options.    Most  resolver  libraries  default
      DNSRCH, DEFNAMES, and RECURSE flags on and all  others
      off.   If  NETINET6 is enabled, most libraries default
      to USE_INET6 as well.  You can also include  "HasWild-
      cardMX"  to specify that there is a wildcard MX record
      matching your domain; this turns off MX matching  when
      canonifying  names,  which  can  lead to inappropriate
      canonifications.   Use   "WorkAroundBrokenAAAA"   when
      faced  with  a a broken nameservers that returns SERV-
      FAIL (a temporary failure) on  T_AAAA  (IPv6)  lookups
      during  hostname  canonification.  Notice: it might be
      necessary to apply the same (or  similar)  options  to










SMM:08-54          Sendmail Installation and Operation Guide


      submit.cf too.

           Version  level  1 configurations (see the section
      about Configuration Version  Level)  turn  DNSRCH  and
      DEFNAMES  off  when  doing delivery lookups, but leave
      them  on  everywhere  else.   Version  8  of  sendmail
      ignores  them  when doing canonification lookups (that
      is, when using $[ ... $]), and always does the search.
      If  you  don't  want  to  do automatic name extension,
      don't call $[ ... $].

           The search rules for $[ ... $] are somewhat  dif-
      ferent than usual.  If the name being looked up has at
      least one dot, it always  tries  the  unmodified  name
      first.   If  that  fails,  it tries the reduced search
      path, and lastly tries the unmodified name  (but  only
      for  names  without a dot, since names with a dot have
      already  been  tried).   This  allows  names  such  as
      ``utc.CS''  to match the site in Czechoslovakia rather
      than the site in your local Computer  Science  depart-
      ment.   It  also  prefers  A and CNAME records over MX
      records -- that is, if it finds an MX record it  makes
      note  of it, but keeps looking.  This way, if you have
      a wildcard MX record matching your domain, it will not
      assume that all names match.

           To  completely turn off all name server access on
      systems without service switch support (such as  SunOS
      4.X)  you  will  have to recompile with -DNAMED_BIND=0
      and remove -lresolv from the list of libraries  to  be
      searched when linking.

   4.11.  Moving the Per-User Forward Files

           Some  sites mount each user's home directory from
      a local disk  on  their  workstation,  so  that  local
      access  is fast.  However, the result is that .forward
      file lookups from a central mail server are slow.   In
      some  cases,  mail  can  even be delivered on machines
      inappropriately because of a file server  being  down.
      The  performance  can be especially bad if you run the
      automounter.

           The ForwardPath (J) option allows you  to  set  a
      path  of  forward files.  For example, the config file
      line

          O ForwardPath=/var/forward/$u:$z/.forward.$w

      would first look for a file with the same name as  the
      user's login in /var/forward; if that is not found (or
      is inaccessible) the file ``.forward.machinename''  in
      the  user's  home  directory  is  searched.   A  truly










Sendmail Installation and Operation Guide          SMM:08-55


      perverse site could also search by sender by using $r,
      $s, or $f.

           If  you  create a directory such as /var/forward,
      it should be mode 1777 (that is, the sticky bit should
      be  set).   Users  should  create the files mode 0644.
      Note that you must use the  ForwardFileInUnsafeDirPath
      and   ForwardFileInUnsafeDirPathSafe  flags  with  the
      DontBlameSendmail option to allow forward files  in  a
      world  writable directory.  This might also be used as
      a denial of service attack (users could create forward
      files  for other users); a better approach might be to
      create /var/forward mode 0755 and create  empty  files
      for  each user, owned by that user, mode 0644.  If you
      do this, you don't have to set  the  DontBlameSendmail
      options indicated above.

   4.12.  Free Space

           On  systems  that have one of the system calls in
      the statfs(2) family (including  statvfs  and  ustat),
      you can specify a minimum number of free blocks on the
      queue filesystem using the MinFreeBlocks  (b)  option.
      If there are fewer than the indicated number of blocks
      free on the filesystem on which the queue  is  mounted
      the  SMTP  server  will reject mail with the 452 error
      code.  This invites  the  SMTP  client  to  try  again
      later.

           Beware  of  setting  this option too high; it can
      cause rejection of email when that mail would be  pro-
      cessed without difficulty.

   4.13.  Maximum Message Size

           To  avoid  overflowing  your  system with a large
      message, the MaxMessageSize option can be set  to  set
      an  absolute  limit  on  the  size of any one message.
      This will be advertised  in  the  ESMTP  dialogue  and
      checked during message collection.

   4.14.  Privacy Flags

           The  PrivacyOptions  (p) option allows you to set
      certain ``privacy'' flags.   Actually,  many  of  them
      don't  give you any extra privacy, rather just insist-
      ing that client SMTP  servers  use  the  HELO  command
      before  using certain commands or adding extra headers
      to indicate possible spoof attempts.

           The option takes a  series  of  flag  names;  the
      final privacy is the inclusive or of those flags.  For
      example:










SMM:08-56          Sendmail Installation and Operation Guide


          O PrivacyOptions=needmailhelo, noexpn

      insists that the HELO or EHLO command be used before a
      MAIL  command  is  accepted and disables the EXPN com-
      mand.

           The flags are detailed in section 5.6.

   4.15.  Send to Me Too

           Beginning with version 8.10, sendmail includes by
      default  the (envelope) sender in any list expansions.
      For example, if "matt" sends to a list  that  contains
      "matt" as one of the members he will get a copy of the
      message.  If the MeToo option is set to FALSE (in  the
      configuration  file  or  via  the  command line), this
      behavior is changed, i.e., the  (envelope)  sender  is
      excluded in list expansions.

5.  THE WHOLE SCOOP ON THE CONFIGURATION FILE

        This  section  describes  the  configuration file in
   detail.

        There is one point that should be made clear immedi-
   ately:  the  syntax of the configuration file is designed
   to be reasonably easy to parse, since this is done  every
   time  sendmail starts up, rather than easy for a human to
   read or write.  The configuration file should  be  gener-
   ated via the method described in cf/README, it should not
   be edited directly unless someone is  familiar  with  the
   internals of the syntax described here and it is not pos-
   sible to achieve  the  desired  result  via  the  default
   method.

        The  configuration  file is organized as a series of
   lines, each of  which  begins  with  a  single  character
   defining  the  semantics for the rest of the line.  Lines
   beginning with a space or a tab  are  continuation  lines
   (although  the  semantics  are  not  well defined in many
   places).  Blank lines and lines beginning  with  a  sharp
   symbol (`#') are comments.

   5.1.  R and S -- Rewriting Rules

           The  core  of  address  parsing are the rewriting
      rules.  These are an ordered production system.  Send-
      mail  scans through the set of rewriting rules looking
      for a match on the left hand side (LHS) of  the  rule.
      When  a  rule  matches, the address is replaced by the
      right hand side (RHS) of the rule.












Sendmail Installation and Operation Guide          SMM:08-57


           There are several sets of rewriting rules.   Some
      of  the  rewriting  sets  are used internally and must
      have specific semantics.  Other rewriting sets do  not
      have  specifically assigned semantics, and may be ref-
      erenced by the mailer definitions or by other  rewrit-
      ing sets.

           The syntax of these two commands are:

          Sn

      Sets the current ruleset being collected to n.  If you
      begin a ruleset more than once it appends to  the  old
      definition.

          Rlhs rhs comments

      The fields must be separated by at least one tab char-
      acter; there may be embedded  spaces  in  the  fields.
      The lhs is a pattern that is applied to the input.  If
      it matches, the input is rewritten to  the  rhs.   The
      comments are ignored.

           Macro  expansions  of  the  form $x are performed
      when the configuration file is read.  A literal $  can
      be  included using $$.  Expansions of the form $&x are
      performed at run time using a  somewhat  less  general
      algorithm.   This  is  intended  only  for referencing
      internally defined macros such as $h that are  changed
      at runtime.

      5.1.1.  The left hand side

              The left hand side of rewriting rules contains
         a  pattern.   Normal  words  are   simply   matched
         directly.   Metasyntax is introduced using a dollar
         sign.  The metasymbols are:

             $*   Match zero or more tokens
             $+   Match one or more tokens
             $-   Match exactly one token
             $=x  Match any phrase in class x
             $~x  Match any word not in class x

         If any of these match, they  are  assigned  to  the
         symbol  $n  for replacement on the right hand side,
         where n is the index in the LHS.  For  example,  if
         the LHS:

             $-:$+

         is applied to the input:











SMM:08-58          Sendmail Installation and Operation Guide


             UCBARPA:eric

         the  rule  will match, and the values passed to the
         RHS will be:

             $1  UCBARPA
             $2  eric


              Additionally, the LHS can include $@ to  match
         zero tokens.  This is not bound to a $n on the RHS,
         and is normally only used when it stands  alone  in
         order to match the null input.

      5.1.2.  The right hand side

              When  the  left  hand side of a rewriting rule
         matches, the input is deleted and replaced  by  the
         right  hand  side.  Tokens are copied directly from
         the RHS unless  they  begin  with  a  dollar  sign.
         Metasymbols are:

             $n         Substitute indefinite token n from LHS
             $[name$]   Canonicalize name
             $(map key $@arguments $:default $)
                        Generalized keyed mapping function
             $>n        "Call" ruleset n
             $#mailer   Resolve to mailer
             $@host     Specify host
             $:user     Specify user


              The  $n  syntax  substitutes the corresponding
         value from a $+, $-, $*, $=, or  $~  match  on  the
         LHS.  It may be used anywhere.

              A  host  name  enclosed  between  $[ and $] is
         looked up in the host database(s) and  replaced  by
         the canonical name14.  For example, "$[ftp$]" might
         become           "ftp.CS.Berkeley.EDU"          and
         "$[[128.32.130.2]$]"     would     become     "van-
         gogh.CS.Berkeley.EDU."    Sendmail  recognizes  its
         numeric IP address without calling the name  server
         and replaces it with its canonical name.

              The  $(  ...  $) syntax is a more general form
         of lookup; it  uses  a  named  map  instead  of  an
         implicit map.  If no lookup is found, the indicated
____________________
   14This  is actually completely equivalent to $(host host-
name$).  In particular, a $: default can be used.












Sendmail Installation and Operation Guide          SMM:08-59


         default is inserted; if no default is specified and
         no  lookup  matches,  the  value is left unchanged.
         The arguments are passed to the  map  for  possible
         use.

              The  $>n  syntax  causes  the remainder of the
         line to be substituted as usual and then passed  as
         the  argument  to  ruleset  n.   The final value of
         ruleset n then becomes the  substitution  for  this
         rule.   The  $> syntax expands everything after the
         ruleset name to the end of the  replacement  string
         and  then  passes  that as the initial input to the
         ruleset.  Recursive calls are allowed.   For  exam-
         ple,

             $>0 $>3 $1

         expands  $1,  passes  that  to  ruleset 3, and then
         passes the result of ruleset 3 to ruleset 0.

              The $# syntax should only be used  in  ruleset
         zero,  a  subroutine  of  ruleset zero, or rulesets
         that  return  decisions  (e.g.,  check_rcpt).    It
         causes evaluation of the ruleset to terminate imme-
         diately, and signals to sendmail that  the  address
         has  completely  resolved.  The complete syntax for
         ruleset 0 is:

             $#mailer $@host $:user

         This specifies the  {mailer,  host,  user}  3-tuple
         necessary  to  direct the mailer.  If the mailer is
         local  the  host part may be omitted15.  The mailer
         must be a single word, but the host and user may be
         multi-part.   If  the  mailer  is  the built-in IPC
         mailer, the host may be a colon-separated  list  of
         hosts  that  are  searched  in  order for the first
         working address (exactly  like  MX  records).   The
         user  is  later  rewritten  by  the mailer-specific
         envelope rewriting  set  and  assigned  to  the  $u
         macro.   As a special case, if the mailer specified
         has the F=@ flag specified and the first  character
         of  the  $:  value is "@", the "@" is stripped off,
         and a flag is set in the  address  descriptor  that
         causes sendmail to not do ruleset 5 processing.

____________________
   15You may want to use it for special  "per  user"  exten-
sions.   For  example, in the address "jgm+foo@CMU.EDU"; the
"+foo" part is not part of the user name, and is  passed  to
the local mailer for local use.












SMM:08-60          Sendmail Installation and Operation Guide


              Normally, a rule that matches is retried, that
         is, the rule loops until it fails.  A RHS may  also
         be  preceded  by a $@ or a $: to change this behav-
         ior.  A $@ prefix causes the ruleset to return with
         the remainder of the RHS as the value.  A $: prefix
         causes the rule to terminate immediately,  but  the
         ruleset to continue; this can be used to avoid con-
         tinued  application  of  a  rule.   The  prefix  is
         stripped before continuing.

              The  $@ and $: prefixes may precede a $> spec;
         for example:

             R$+     $: $>7 $1

         matches anything, passes that to ruleset seven, and
         continues; the $: is necessary to avoid an infinite
         loop.

              Substitution occurs in  the  order  described,
         that  is,  parameters from the LHS are substituted,
         hostnames  are  canonicalized,  "subroutines"   are
         called, and finally $#, $@, and $: are processed.

      5.1.3.  Semantics of rewriting rule sets

              There  are  six  rewriting sets that have spe-
         cific semantics.  Five  of  these  are  related  as
         depicted by figure 1.


____________________________________________________________

                    +---+
                 -->| 0 |-->resolved address
                /   +---+
               /            +---+   +---+
              /        ---->| 1 |-->| S |--
       +---+ / +---+  /     +---+   +---+  \    +---+
addr-->| 3 |-->| D |--                      --->| 4 |-->msg
       +---+   +---+  \     +---+   +---+  /    +---+
                        --->| 2 |-->| R |--
                            +---+   +---+

            Figure 1 -- Rewriting set semantics
          D -- sender domain addition
          S -- mailer-specific sender rewriting
          R -- mailer-specific recipient rewriting
____________________________________________________________














Sendmail Installation and Operation Guide          SMM:08-61


              Ruleset  three  should  turn  the address into
         "canonical form."  This form should have the  basic
         syntax:

             local-part@host-domain-spec

         Ruleset  three  is applied by sendmail before doing
         anything with any address.

              If no "@" sign is specified,  then  the  host-
         domain-spec  may  be appended (box "D" in Figure 1)
         from the sender address (if the C flag  is  set  in
         the  mailer definition corresponding to the sending
         mailer).

              Ruleset zero is applied after ruleset three to
         addresses that are going to actually specify recip-
         ients.   It  must  resolve  to  a  {mailer,   host,
         address} triple.  The mailer must be defined in the
         mailer definitions  from  the  configuration  file.
         The  host  is  defined into the $h macro for use in
         the argv expansion of the specified mailer.

              Rulesets one and two are applied to all sender
         and  recipient  addresses  respectively.   They are
         applied before any specification in the mailer def-
         inition.  They must never resolve.

              Ruleset  four  is  applied to all addresses in
         the message.  It is  typically  used  to  translate
         internal to external form.

              In addition, ruleset 5 is applied to all local
         addresses (specifically, those that  resolve  to  a
         mailer  with  the  `F=5' flag set) that do not have
         aliases.  This allows a last minute hook for  local
         names.

      5.1.4.  Ruleset hooks

              A  few  extra  rulesets are defined as "hooks"
         that can be defined to get special features.   They
         are  all  named  rulesets.  The "check_*" forms all
         give accept/reject status; falling off the  end  or
         returning  normally  is an accept, and resolving to
         $#error is  a  reject.   Many  of  these  can  also
         resolve  to the special mailer name $#discard; this
         accepts the message as though  it  were  successful
         but  then discards it without delivery.  Note, this
         mailer cannot be chosen as a mailer in  ruleset  0.
         Note  also that all "check_*" rulesets have to deal
         with  temporary  failures,   especially   for   map
         lookups,  themselves,  i.e.,  they  should return a










SMM:08-62          Sendmail Installation and Operation Guide


         temporary error code or at least they should make a
         proper decision in those cases.

         5.1.4.1.  check_relay

                 The  check_relay  ruleset is called after a
            connection is accepted by the daemon.  It is not
            called  when  sendmail  is started using the -bs
            option.  It is passed

                client.host.name $| client.host.address

            where $| is a metacharacter separating  the  two
            parts.  This ruleset can reject connections from
            various locations.

         5.1.4.2.  check_mail

                 The check_mail ruleset is passed  the  user
            name parameter of the SMTP MAIL command.  It can
            accept or reject the address.

         5.1.4.3.  check_rcpt

                 The check_rcpt ruleset is passed  the  user
            name parameter of the SMTP RCPT command.  It can
            accept or reject the address.

         5.1.4.4.  check_data

                 The check_data ruleset is called after  the
            SMTP  DATA  command, its parameter is the number
            of recipients.  It can accept or reject the com-
            mand.

         5.1.4.5.  check_compat

                 The check_compat ruleset is passed

                sender-address $| recipient-address

            where  $|  is  a  metacharacter  separating  the
            addresses.  It can accept or reject mail  trans-
            fer  between  these  two addresses much like the
            checkcompat() function.

         5.1.4.6.  check_eoh

                 The check_eoh ruleset is passed

                number-of-headers $| size-of-headers

            where  $|  is  a  metacharacter  separating  the










Sendmail Installation and Operation Guide          SMM:08-63


            numbers.   These  numbers  can  be used for size
            comparisons with the arith map.  The ruleset  is
            triggered  after  all  of  the headers have been
            read.  It can be used to  correlate  information
            gathered  from  those  headers  using  the macro
            storage map.  One possible use is to check for a
            missing header.  For example:

                Kstorage macro
                HMessage-Id: $>CheckMessageId

                SCheckMessageId
                # Record the presence of the header
                R$*            $: $(storage {MessageIdCheck} $@ OK $) $1
                R< $+ @ $+ >   $@ OK
                R$*            $#error $: 553 Header Error

                Scheck_eoh
                # Check the macro
                R$*            $: < $&{MessageIdCheck} >
                # Clear the macro for the next message
                R$*            $: $(storage {MessageIdCheck} $) $1
                # Has a Message-Id: header
                R< $+ >        $@ OK
                # Allow missing Message-Id: from local mail
                R$*            $: < $&{client_name} >
                R< >           $@ OK
                R< $=w >       $@ OK
                # Otherwise, reject the mail
                R$*            $#error $: 553 Header Error

            Keep  in  mind  the  Message-Id: header is not a
            required header and is  not  a  guaranteed  spam
            indicator.   This  ruleset  is  an  example  and
            should probably not be used in production.

         5.1.4.7.  check_etrn

                 The check_etrn ruleset is passed the param-
            eter of the SMTP ETRN command.  It can accept or
            reject the command.

         5.1.4.8.  check_expn

                 The check_expn ruleset is passed  the  user
            name parameter of the SMTP EXPN command.  It can
            accept or reject the address.

         5.1.4.9.  check_vrfy

                 The check_vrfy ruleset is passed  the  user
            name parameter of the SMTP VRFY command.  It can
            accept or reject the command.










SMM:08-64          Sendmail Installation and Operation Guide


         5.1.4.10.  trust_auth

                 The trust_auth ruleset is passed the  AUTH=
            parameter  of the SMTP MAIL command.  It is used
            to  determine  whether  this  value  should   be
            trusted.  In  order  to  make this decision, the
            ruleset may make use of  the  various  ${auth_*}
            macros.   If  the  ruleset  does  resolve to the
            "error"  mailer  the  AUTH=  parameter  is   not
            trusted  and  hence  not  passed  on to the next
            relay.

         5.1.4.11.  tls_client

                 The tls_client ruleset is called when send-
            mail  acts  as  server, after a STARTTLS command
            has  been  issued,  and  from  check_mail.   The
            parameter is the value of ${verify} and STARTTLS
            or MAIL,  respectively.   If  the  ruleset  does
            resolve  to  the "error" mailer, the appropriate
            error code is returned to the client.

         5.1.4.12.  tls_server

                 The tls_server ruleset is called when send-
            mail  acts  as  client  after a STARTTLS command
            (should) have been issued.  The parameter is the
            value of ${verify}.  If the ruleset does resolve
            to the "error" mailer, the connection is aborted
            (treated  as non-deliverable with a permanent or
            temporary error).

         5.1.4.13.  tls_rcpt

                 The tls_rcpt ruleset is  called  each  time
            before a RCPT TO command is sent.  The parameter
            is the current recipient.  If the  ruleset  does
            resolve  to the "error" mailer, the RCPT TO com-
            mand is suppressed (treated  as  non-deliverable
            with  a  permanent  or  temporary  error).  This
            ruleset allows to require encryption or  verifi-
            cation  of  the recipient's MTA even if the mail
            is somehow  redirected  to  another  host.   For
            example,  sending  mail  to luke@endmail.org may
            get redirected to a host  named  death.star  and
            hence  the  tls_server  ruleset won't apply.  By
            introducing  per  recipient  restrictions   such
            attacks  (e.g.,  via  DNS  spoofing) can be made
            impossible.  See cf/README how this ruleset  can
            be used.













Sendmail Installation and Operation Guide          SMM:08-65


         5.1.4.14.  srv_features

                 The  srv_features  ruleset is called when a
            client  connects  to  sendmail.   This   ruleset
            should  return  $# followed by a list of options
            (single characters delimited  by  white  space).
            If the return value starts with anything else it
            is silently ignored.  Generally upper case char-
            acters turn off a feature while lower case char-
            acters turn it on.  The option  `S'  causes  the
            server not to offer STARTTLS.  This is useful to
            interact with MTAs/MUAs that have broken  START-
            TLS  implementations  by simply not offering it.
            `V' turns off the request for a client  certifi-
            cate  during  the TLS handshake.  Option `A' and
            `P' suppress SMTP AUTH and  PIPELINING,  respec-
            tively.   The  ruleset  may  return  `$#temp' to
            indicate  that  there  is  a  temporary  problem
            determining the correct features, e.g., if a map
            is unavailable.  In that case, the  SMTP  server
            issues  a  temporary failure and does not accept
            email.

         5.1.4.15.  try_tls

                 The try_tls ruleset is called when sendmail
            connects  to  another  MTA.  If the ruleset does
            resolve to the "error" mailer, sendmail does not
            try  STARTTLS  even  if  it is offered.  This is
            useful to interact with MTAs  that  have  broken
            STARTTLS implementations by simply not using it.

         5.1.4.16.  authinfo

                 The authinfo ruleset is called  when  send-
            mail  tries  to authenticate to another MTA.  It
            should return $# followed by a  list  of  tokens
            that  are  used  for  SMTP  AUTH.  If the return
            value starts with anything else it  is  silently
            ignored.   Each  token is a tagged string of the
            form: "TDstring" (including the quotes), where

                T        Tag which describes the item
                D        Delimiter: ':' simple text follows
                         '=' string is base64 encoded
                string   Value of the item

            Valid values for the tag are:















SMM:08-66          Sendmail Installation and Operation Guide


                U        user (authorization) id
                I        authentication id
                P        password
                R        realm
                M        list of mechanisms delimited by spaces

            If this ruleset is defined, the option  Default-
            AuthInfo  is  ignored  (even if the ruleset does
            not return a ``useful'' result).

         5.1.4.17.  queuegroup

                 The queuegroup ruleset is used  to  map  an
            address to a queue group name.  It should return
            $# followed by the name of a  queue  group.   If
            the return value starts with anything else it is
            silently ignored.  See the section  about  Queue
            Groups  and Queue Directories for further infor-
            mation.

      5.1.5.  IPC mailers

              Some special processing occurs if the  ruleset
         zero  resolves  to an IPC mailer (that is, a mailer
         that has "[IPC]" listed as the Path in the  M  con-
         figuration  line.   The host name passed after "$@"
         has MX expansion performed if not delivering via  a
         named socket; this looks the name up in DNS to find
         alternate delivery sites.

              The host name can also be provided as a dotted
         quad  or  an  IPv6  address in square brackets; for
         example:

             [128.32.149.78]

         or

             [IPv6:2002:c0a8:51d2::23f4]

         This causes direct conversion of the numeric  value
         to an IP host address.

              The  host  name  passed  in after the "$@" may
         also be a colon-separated list of hosts.   Each  is
         separately MX expanded and the results are concate-
         nated to make (essentially) one long MX list.   The
         intent here is to create "fake" MX records that are
         not published in DNS for private internal networks.

              As  a final special case, the host name can be
         passed in as a text string in square brackets:











Sendmail Installation and Operation Guide          SMM:08-67


             [ucbvax.berkeley.edu]

         This form avoids the MX  mapping.   N.B.:  This  is
         intended  only for situations where you have a net-
         work firewall or other host that  will  do  special
         processing  for  all  your  mail,  so  that your MX
         record points to a gateway  machine;  this  machine
         could  then  do  direct delivery to machines within
         your local domain.  Use of  this  feature  directly
         violates  RFC  1123 section 5.3.5: it should not be
         used lightly.

   5.2.  D -- Define Macro

           Macros are named with a single character or  with
      a  word  in  {braces}.   The  names  ``x'' and ``{x}''
      denote the  same  macro  for  every  single  character
      ``x''.   Single  character  names may be selected from
      the entire ASCII set, but user-defined  macros  should
      be  selected  from the set of upper case letters only.
      Lower case letters and special symbols are used inter-
      nally.   Long names beginning with a lower case letter
      or a punctuation character are  reserved  for  use  by
      sendmail,  so  user-defined  long  macro  names should
      begin with an upper case letter.

           The syntax for macro definitions is:

          Dxval

      where x is the name of the macro (which may be a  sin-
      gle  character  or  a  word  in braces) and val is the
      value it should have.  There should be no spaces given
      that do not actually belong in the macro value.

           Macros  are  interpolated using the construct $x,
      where x is the name of the macro to  be  interpolated.
      This interpolation is done when the configuration file
      is read, except in M lines.  The special construct $&x
      can  be used in R lines to get deferred interpolation.

           Conditionals can be specified using the syntax:

          $?x text1 $| text2 $.

      This interpolates text1 if the macro  $x  is  set  and
      non-null, and text2 otherwise.  The "else" ($|) clause
      may be omitted.

           The following  macros  are  defined  and/or  used
      internally  by  sendmail for interpolation into argv's
      for mailers or for other contexts.  The ones marked  *











SMM:08-68          Sendmail Installation and Operation Guide


      are  information  passed  into  sendmail16,  the  ones
      marked # are information passed both  in  and  out  of
      sendmail,  and  the  unmarked macros are passed out of
      sendmail but are not otherwise used internally.  These
      macros are:

      $a   The  origination date in RFC 822 format.  This is
           extracted from the Date: line.

      $b   The current date in RFC 822 format.

      $c   The hop count.  This is a count of the number  of
           Received:  lines plus the value of the -h command
           line flag.

      $d   The current date in UNIX (ctime) format.

      $e*  (Obsolete;   use    SmtpGreetingMessage    option
           instead.)   The  SMTP  entry  message.   This  is
           printed out when SMTP starts up.  The first  word
           must  be  the  $j  macro as specified by RFC 821.
           Defaults to "$j Sendmail $v ready at  $b".   Com-
           monly redefined to include the configuration ver-
           sion number, e.g., "$j Sendmail  $v/$Z  ready  at
           $b"

      $f   The envelope sender (from) address.

      $g   The  sender  address  relative  to the recipient.
           For  example,  if  $f  is  "foo",  $g   will   be
           "host!foo",  "foo@host.domain",  or  whatever  is
           appropriate for the receiving mailer.

      $h   The recipient host.  This is  set  in  ruleset  0
           from the $@ field of a parsed address.

      $i   The queue id, e.g., "f344MXxp018717".

      $j#  The  "official"  domain name for this site.  This
           is fully qualified if the full qualification  can
           be  found.   It must be redefined to be the fully
           qualified domain name if your system is not  con-
           figured so that information can find it automati-
           cally.

      $k   The UUCP node name (from the uname system  call).

      $l*  (Obsolete; use UnixFromLine option instead.)  The
           format of the UNIX from line.   Unless  you  have
____________________
   16As  of version 8.6, all of these macros have reasonable
defaults.  Previous versions required that they be  defined.











Sendmail Installation and Operation Guide          SMM:08-69


           changed  the  UNIX mailbox format, you should not
           change the default, which is "From $g $d".

      $m   The domain part of the gethostname return  value.
           Under  normal  circumstances, $j is equivalent to
           $w.$m.

      $n*  The name of  the  daemon  (for  error  messages).
           Defaults to "MAILER-DAEMON".

      $o*  (Obsolete:  use  OperatorChars  option  instead.)
           The set of "operators" in addresses.  A  list  of
           characters  which  will  be considered tokens and
           which will separate tokens  when  doing  parsing.
           For  example,  if  "@" were in the $o macro, then
           the input "a@b" would be scanned as three tokens:
           "a," "@," and "b."  Defaults to ".:@[]", which is
           the minimum set necessary to do RFC 822  parsing;
           a  richer  set  of operators is ".:%@!/[]", which
           adds support for  UUCP,  the  %-hack,  and  X.400
           addresses.

      $p   Sendmail's process id.

      $q*  Default  format  of sender address.  The $q macro
           specifies how an address should appear in a  mes-
           sage  when  it is defaulted.  Defaults to "<$g>".
           It is commonly redefined to be "$?x$x <$g>$|$g$."
           or "$g$?x ($x)$.", corresponding to the following
           two formats:

               Eric Allman <eric@CS.Berkeley.EDU>
               eric@CS.Berkeley.EDU (Eric Allman)

           Sendmail properly quotes names that have  special
           characters if the first form is used.

      $r   Protocol  used  to receive the message.  Set from
           the -p command line flag or by  the  SMTP  server
           code.

      $s   Sender's host name.  Set from the -p command line
           flag or by the SMTP server code.

      $t   A numeric representation of the current time.

      $u   The recipient user.

      $v   The version number of the sendmail binary.

      $w#  The hostname of this site.  This is the root name
           of this host (but see below for caveats).











SMM:08-70          Sendmail Installation and Operation Guide


      $x   The full name of the sender.

      $z   The home directory of the recipient.

      $_   The   validated   sender   address.    See   also
           ${client_resolve}.

      ${addr_type}
           The type of the address which is currently  being
           rewritten.  This macro contains up to three char-
           acters, the first is either `e' or `h' for  enve-
           lope/header  address,  the second is a space, and
           the third is either `s' or `r' for sender/recipi-
           ent  address.   Notice:  for  header addresses no
           distinction is currently made between sender  and
           recipient  addresses,  i.e.,  the  macro contains
           only `h'.

      ${alg_bits}
           The maximum keylength (in bits) of the  symmetric
           encryption  algorithm  used for a TLS connection.
           This may be less than  the  effective  keylength,
           which  is  stored in ${cipher_bits}, for ``export
           controlled'' algorithms.

      ${auth_authen}
           The client's authentication credentials as deter-
           mined by authentication (only set if successful).
           The format depends  on  the  mechanism  used,  it
           might  be  just `user', or `user@realm', or some-
           thing similar (SMTP AUTH only).

      ${auth_author}
           The authorization identity, i.e. the AUTH= param-
           eter of the SMTP MAIL command if supplied.

      ${auth_type}
           The  mechanism used for SMTP authentication (only
           set if successful).

      ${auth_ssf}
           The keylength (in bits) of the symmetric  encryp-
           tion  algorithm  used for the security layer of a
           SASL mechanism.

      ${bodytype}
           The message body  type  (7BIT  or  8BITMIME),  as
           determined from the envelope.

      ${cert_issuer}
           The  DN  (distinguished name) of the CA (certifi-
           cate authority) that signed  the  presented  cer-
           tificate (the cert issuer) (STARTTLS only).










Sendmail Installation and Operation Guide          SMM:08-71


      ${cert_md5}
           The MD5 hash of the presented certificate (START-
           TLS only).

      ${cert_subject}
           The DN of the presented certificate  (called  the
           cert subject) (STARTTLS only).

      ${cipher}
           The  cipher  suite used for the connection, e.g.,
           EDH-DSS-DES-CBC3-SHA,  EDH-RSA-DES-CBC-SHA,  DES-
           CBC-MD5, DES-CBC3-SHA (STARTTLS only).

      ${cipher_bits}
           The  effective keylength (in bits) of the symmet-
           ric encryption algorithm used for a  TLS  connec-
           tion.

      ${client_addr}
           The   IP   address  of  the  SMTP  client.   IPv6
           addresses are  tagged  with  "IPv6:"  before  the
           address.  Defined in the SMTP server only.

      ${client_name}
           The  host  name  of the SMTP client.  This may be
           the client's bracketed IP address in the  form  [
           nnn.nnn.nnn.nnn     ]     for    IPv4    and    [
           IPv6:nnnn:...:nnnn ] for IPv6 if the client's  IP
           address is not resolvable, or if it is resolvable
           but the  IP  address  of  the  resolved  hostname
           doesn't  match  the original IP address.  Defined
           in   the   SMTP   server    only.     See    also
           ${client_resolve}.

      ${client_port}
           The  port  number of the SMTP client.  Defined in
           the SMTP server only.

      ${client_resolve}
           Holds  the  result  of  the  resolve   call   for
           ${client_name}.  Possible values are:

               OK        resolved successfully
               FAIL      permanent lookup failure
               FORGED    forward lookup doesn't match reverse lookup
               TEMP      temporary lookup failure

           Defined  in  the SMTP server only.  sendmail per-
           forms a hostname lookup on the IP address of  the
           connecting client.  Next the IP addresses of that
           hostname are looked up.  If the client IP address
           does  not  appear in that list, then the hostname
           is maybe forged.  This is reflected as the  value










SMM:08-72          Sendmail Installation and Operation Guide


           FORGED for ${client_resolve} and it also shows up
           in $_ as "(may be forged)".

      ${cn_issuer}
           The CN (common name) of the CA  that  signed  the
           presented certificate (STARTTLS only).

      ${cn_subject}
           The CN (common name) of the presented certificate
           (STARTTLS only).

      ${currHeader}
           Header value as quoted string (possibly truncated
           to  MAXNAME).   This  macro  is only available in
           header check rulesets.

      ${daemon_addr}
           The IP address the daemon  is  listening  on  for
           connections.

      ${daemon_family}
           The  network  family  if  the daemon is accepting
           network  connections.   Possible  values  include
           "inet", "inet6", "iso", "ns", "x.25"

      ${daemon_flags}
           The flags for the daemon as specified by the Mod-
           ifier=  part  of  DaemonPortOptions  whereby  the
           flags  are  separated  from each other by spaces,
           and upper case flags are doubled.  That is, Modi-
           fier=Ea  will  be represented as "EE a" in ${dae-
           mon_flags}, which is  required  for  testing  the
           flags in rulesets.

      ${daemon_info}
           Some information about a daemon as a text string.
           For example, "SMTP+queueing@00:30:00".

      ${daemon_name}
           The name of  the  daemon  from  DaemonPortOptions
           Name=  suboption.   If this suboption is not set,
           "Daemon#", where # is the daemon number, is used.

      ${daemon_port}
           The  port  the daemon is accepting connection on.
           Unless DaemonPortOptions is set, this  will  most
           likely be "25".

      ${deliveryMode}
           The  current delivery mode sendmail is using.  It
           is initially set to the value of the DeliveryMode
           option.











Sendmail Installation and Operation Guide          SMM:08-73


      ${envid}
           The  envelope  id  parameter  (ENVID=)  passed to
           sendmail as part of the envelope.

      ${hdrlen}
           The length of the header value which is stored in
           ${currHeader}  (before  possible truncation).  If
           this value is greater than or  equal  to  MAXNAME
           the header has been truncated.

      ${hdr_name}
           The  name  of the header field for which the cur-
           rent header check ruleset has been called.   This
           is  useful  for a default header check ruleset to
           get the name of the header;  the  macro  is  only
           available in header check rulesets.

      ${if_addr}
           The  IP  address  of the interface of an incoming
           connection unless it  is  in  the  loopback  net.
           IPv6 addresses are tagged with "IPv6:" before the
           address.

      ${if_addr_out}
           The IP address of the interface  of  an  outgoing
           connection  unless  it  is  in  the loopback net.
           IPv6 addresses are tagged with "IPv6:" before the
           address.

      ${if_family}
           The  IP  family  of  the interface of an incoming
           connection unless it is in the loopback net.

      ${if_family_out}
           The IP family of the  interface  of  an  outgoing
           connection unless it is in the loopback net.

      ${if_name}
           The  hostname associated with the interface of an
           incoming connection.  This macro can be used  for
           SmtpGreetingMessage  and  HReceived  for  virtual
           hosting.  For example:

               O SmtpGreetingMessage=$?{if_name}${if_name}$|$j$. MTA


      ${if_name_out}
           The name of the interface of an outgoing  connec-
           tion.

      ${mail_addr}
           The  address  part  of the resolved triple of the
           address given for the SMTP MAIL command.  Defined










SMM:08-74          Sendmail Installation and Operation Guide


           in the SMTP server only.

      ${mail_host}
           The  host from the resolved triple of the address
           given for the SMTP MAIL command.  Defined in  the
           SMTP server only.

      ${mail_mailer}
           The  mailer  from  the  resolved  triple  of  the
           address given for the SMTP MAIL command.  Defined
           in the SMTP server only.

      ${msg_size}
           The  value  of the SIZE= parameter, i.e., usually
           the size of the message (in an  ESMTP  dialogue),
           before the message has been collected, thereafter
           the message size as computed by sendmail (and can
           be used in check_compat).

      ${nrcpts}
           The  number  of validated recipients for a single
           message.  Note: since recipient  validation  hap-
           pens  after check_rcpt has been called, the value
           in this ruleset is one less than  what  might  be
           expected.

      ${ntries}
           The number of delivery attempts.

      ${opMode}
           The current operation mode (from the -b flag).

      ${queue_interval}
           The queue run interval given by the -q flag.  For
           example, -q30m  would  set  ${queue_interval}  to
           "00:30:00".

      ${rcpt_addr}
           The  address  part  of the resolved triple of the
           address given for the SMTP RCPT command.  Defined
           in the SMTP server only after a RCPT command.

      ${rcpt_host}
           The  host from the resolved triple of the address
           given for the SMTP RCPT command.  Defined in  the
           SMTP server only after a RCPT command.

      ${rcpt_mailer}
           The  mailer  from  the  resolved  triple  of  the
           address given for the SMTP RCPT command.  Defined
           in the SMTP server only after a RCPT command.












Sendmail Installation and Operation Guide          SMM:08-75


      ${server_addr}
           The address of the server of the current outgoing
           SMTP connection.  For LMTP delivery the macro  is
           set to the name of the mailer.

      ${server_name}
           The  name  of  the server of the current outgoing
           SMTP or LMTP connection.

      ${tls_version}
           The TLS/SSL  version  used  for  the  connection,
           e.g., TLSv1, SSLv3, SSLv2; defined after STARTTLS
           has been used.

      ${verify}
           The result of the verification of  the  presented
           cert;  only defined after STARTTLS has been used.
           Possible values are:

               OK           verification succeeded.
               NO           no cert presented.
               NOT          no cert requested.
               FAIL         cert presented but could not be verified,
                            e.g., the signing CA is missing.
               NONE         STARTTLS has not been performed.
               TEMP         temporary error occurred.
               PROTOCOL     some protocol error occurred.
               SOFTWARE     STARTTLS handshake failed,
                            which is a fatal error for this session,
                            the e-mail will be queued.


           There are three types of dates that can be  used.
      The  $a and $b macros are in RFC 822 format; $a is the
      time as extracted from the "Date:" line of the message
      (if  there  was  one),  and $b is the current date and
      time (used for postmarks).   If  no  "Date:"  line  is
      found  in  the incoming message, $a is set to the cur-
      rent time also.  The $d macro is equivalent to the  $b
      macro in UNIX (ctime) format.

           The macros $w, $j, and $m are set to the identity
      of this host.  Sendmail tries to find the fully quali-
      fied name of the host if at all possible; it does this
      by calling gethostname(2) to get the current  hostname
      and  then  passing  that  to gethostbyname(3) which is
      supposed to return the canonical version of that  host
      name.17  Assuming this is successful, $j is set to the
____________________
   17For  example,  on some systems gethostname might return
"foo" which would be mapped to "foo.bar.com"  by  gethostby-
name.











SMM:08-76          Sendmail Installation and Operation Guide


      fully qualified name and $m is set to the domain  part
      of  the name (everything after the first dot).  The $w
      macro is set to the first word (everything before  the
      first  dot) if you have a level 5 or higher configura-
      tion file; otherwise, it is set to the same  value  as
      $j.   If  the  canonification is not successful, it is
      imperative that the config file set $j  to  the  fully
      qualified domain name18.

           The $f macro is the id of the  sender  as  origi-
      nally  determined; when mailing to a specific host the
      $g macro is set to the address of the sender  relative
      to  the  recipient.   For  example, if I send to "bol-
      lard@matisse.CS.Berkeley.EDU" from the  machine  "van-
      gogh.CS.Berkeley.EDU"  the $f macro will be "eric" and
      the $g macro will be "eric@vangogh.CS.Berkeley.EDU."

           The $x macro is set  to  the  full  name  of  the
      sender.   This  can be determined in several ways.  It
      can be passed as flag to sendmail.  It can be  defined
      in the NAME environment variable.  The third choice is
      the value of the "Full-Name:" line in the header if it
      exists,  and the fourth choice is the comment field of
      a "From:" line.  If all of these fail, and if the mes-
      sage  is  being  originated  locally, the full name is
      looked up in the /etc/passwd file.

           When sending, the $h, $u, and $z macros  get  set
      to  the  host,  user, and home directory (if local) of
      the recipient.  The first two are set from the $@  and
      $: part of the rewriting rules, respectively.

           The  $p  and  $t macros are used to create unique
      strings (e.g., for the "Message-Id:" field).   The  $i
      macro is set to the queue id on this host; if put into
      the timestamp line it  can  be  extremely  useful  for
      tracking messages.  The $v macro is set to be the ver-
      sion number of  sendmail;  this  is  normally  put  in
      timestamps  and  has  been proven extremely useful for
      debugging.

           The $c field is set to the "hop count," i.e., the
      number of times this message has been processed.  This
      can be determined by the -h flag on the  command  line
      or by counting the timestamps in the message.

           The $r and $s fields are set to the protocol used
      to communicate with sendmail and the sending hostname.
____________________
   18Older versions of sendmail didn't pre-define $j at all,
so up until 8.6, config files always had to define $j.












Sendmail Installation and Operation Guide          SMM:08-77


      They  can  be  set  together using the -p command line
      flag or separately using the -M or -oM flags.

           The $_ is set to a validated  sender  host  name.
      If  the  sender is running an RFC 1413 compliant IDENT
      server and the receiver has the IDENT protocol  turned
      on, it will include the user name on that host.

           The     ${client_name},    ${client_addr},    and
      ${client_port} macros are set to  the  name,  address,
      and  port  number  of  the SMTP client who is invoking
      sendmail as a  server.   These  can  be  used  in  the
      check_*  rulesets  (using  the  $& deferred evaluation
      form, of course!).

   5.3.  C and F -- Define Classes

           Classes of phrases may be defined to match on the
      left hand side of rewriting rules, where a "phrase" is
      a sequence of characters that does not  contain  space
      characters.   For  example  a class of all local names
      for this site might be created  so  that  attempts  to
      send  to  oneself can be eliminated.  These can either
      be defined directly in the configuration file or  read
      in  from  another file.  Classes are named as a single
      letter or a word in {braces}.  Class  names  beginning
      with  lower  case  letters  and special characters are
      reserved for system use.  Classes  defined  in  config
      files  may  be  given names from the set of upper case
      letters for short names or  beginning  with  an  upper
      case letter for long names.

           The syntax is:

          Ccphrase1 phrase2...
          Fcfile
          Fc|program
          Fc[mapkey]@mapclass:mapspec

      The first form defines the class c to match any of the
      named words.  If phrase1 or phrase2 is another  class,
      e.g.,  $=S, the contents of class S are added to class
      c.  It is permissible to  split  them  among  multiple
      lines; for example, the two forms:

          CHmonet ucbmonet

      and

          CHmonet
          CHucbmonet

      are  equivalent.  The ``F'' forms read the elements of










SMM:08-78          Sendmail Installation and Operation Guide


      the class c from the named file, program, or map spec-
      ification.   Each  element should be listed on a sepa-
      rate line.  To specify an optional  file,  use  ``-o''
      between the class name and the file name, e.g.,

          Fc -o /path/to/file

      If  the file can't be used, sendmail will not complain
      but silently ignore it.  The map  form  should  be  an
      optional map key, an at sign, and a map class followed
      by the specification for that map.  Examples include:

          F{VirtHosts}@ldap:-k (&(objectClass=virtHosts)(host=*)) -v host
          F{MyClass}foo@hash:/etc/mail/classes

      will fill the class $={VirtHosts}  from  an  LDAP  map
      lookup and $={MyClass} from a hash database map lookup
      of the foo.  There is also a built-in schema that  can
      be accessed by only specifying:

          F{ClassName}@LDAP

      This will tell sendmail to use the default schema:

          -k (&(objectClass=sendmailMTAClass)
               (sendmailMTAClassName=ClassName)
               (|(sendmailMTACluster=${sendmailMTACluster})
                 (sendmailMTAHost=$j)))
          -v sendmailMTAClassValue

      Note  that  the  lookup  is only done when sendmail is
      initially started.

           Elements of classes  can  be  accessed  in  rules
      using  $=  or $~.  The $~ (match entries not in class)
      only matches a single word; multi-word entries in  the
      class are ignored in this context.

           Some classes have internal meaning to sendmail:

      $=e  contains  the Content-Transfer-Encodings that can
           be 8->7 bit encoded.  It is predefined to contain
           "7bit", "8bit", and "binary".

      $=k  set  to be the same as $k, that is, the UUCP node
           name.

      $=m  set to the set of domains by which this  host  is
           known, initially just $m.

      $=n  can be set to the set of MIME body types that can
           never be eight to seven bit encoded.  It defaults
           to "multipart/signed".  Message types "message/*"










Sendmail Installation and Operation Guide          SMM:08-79


           and "multipart/*"  are  never  encoded  directly.
           Multipart  messages  are  always  handled  recur-
           sively.  The handling of message/*  messages  are
           controlled by class $=s.

      $=q  A set of Content-Types that will never be encoded
           as base64 (if they have to be encoded, they  will
           be  encoded  as  quoted-printable).   It can have
           primary types (e.g., "text") or full types  (such
           as  "text/plain").   The  class is initialized to
           have "text/plain" only.

      $=s  contains the set of subtypes of message that  can
           be  treated  recursively.  By default it contains
           only "rfc822".  Other "message/*" types cannot be
           8->7  bit encoded.  If a message containing eight
           bit data is sent to a seven bit  host,  and  that
           message  cannot  be  encoded  into seven bits, it
           will be stripped to 7 bits.

      $=t  set to the set of trusted users by the T configu-
           ration  line.   If you want to read trusted users
           from a file, use Ft/file/name.

      $=w  set to be the set of all names this host is known
           by.  This can be used to match local hostnames.

      $={persistentMacros}
           set  to  the  macros would should be saved across
           queue runs.  Care should  be  taken  when  adding
           macro names to this class.

           Sendmail  can  be  compiled  to  allow a scanf(3)
      string on the F line.  This  lets  you  do  simplistic
      parsing  of  text files.  For example, to read all the
      user names in your  system  /etc/passwd  file  into  a
      class, use

          FL/etc/passwd %[^:]

      which reads every line up to the first colon.

   5.4.  M -- Define Mailer

           Programs and interfaces to mailers are defined in
      this line.  The format is:

          Mname, {field=value}*

      where name is the name of the mailer (used  internally
      only)  and the "field=name" pairs define attributes of
      the mailer.  Fields are:











SMM:08-80          Sendmail Installation and Operation Guide


          Path      The pathname of the mailer
          Flags     Special flags for this mailer
          Sender    Rewriting set(s) for sender addresses
          Recipient Rewriting set(s) for recipient addresses
          recipientsMaximum number of recipients per connection
          Argv      An argument vector to pass to this mailer
          Eol       The end-of-line string for this mailer
          Maxsize   The maximum message length to this mailer
          maxmessagesThe maximum message deliveries per connection
          Linelimit The maximum line length in the message body
          Directory The working directory for the mailer
          Userid    The default user and group id to run as
          Nice      The nice(2) increment for the mailer
          Charset   The default character set for 8-bit characters
          Type      Type information for DSN diagnostics
          Wait      The maximum time to wait for the mailer
          QueuegroupThe default queue group for the mailer
          /         The root directory for the mailer

      Only the first character of the field name is  checked
      (it's case-sensitive).

           The  following  flags  may  be  set in the mailer
      description.  Any other flags may be  used  freely  to
      conditionally  assign headers to messages destined for
      particular mailers.   Flags  marked  with  *  are  not
      interpreted by the sendmail binary; these are the con-
      ventionally used to correlate to the flags portion  of
      the  H line.  Flags marked with # apply to the mailers
      for the sender address rather than the usual recipient
      mailers.

      a   Run  Extended  SMTP  (ESMTP)  protocol (defined in
          RFCs 1869, 1652, and 1870).  This flag defaults on
          if  the  SMTP  greeting  message includes the word
          "ESMTP".

      A   Look up the user part of the address in the  alias
          database.   Normally  this  is  only set for local
          mailers.

      b   Force a blank line on the end of a message.   This
          is intended to work around some stupid versions of
          /bin/mail that require a blank line,  but  do  not
          provide  it  themselves.  It would not normally be
          used on network mail.

      c   Do not include comments in addresses.  This should
          only  be  used if you have to work around a remote
          mailer  that  gets  confused  by  comments.   This
          strips addresses of the form "Phrase <address>" or
          "address (Comment)" down to just "address".











Sendmail Installation and Operation Guide          SMM:08-81


      C#  If mail is received from a mailer with  this  flag
          set,  any addresses in the header that do not have
          an at sign ("@") after being rewritten by  ruleset
          three  will  have  the  "@domain"  clause from the
          sender envelope address tacked  on.   This  allows
          mail with headers of the form:

              From: usera@hosta
              To: userb@hostb, userc

          to be rewritten as:

              From: usera@hosta
              To: userb@hostb, userc@hosta

          automatically.   However,  it  doesn't really work
          reliably.

      d   Do not include angle brackets around route-address
          syntax  addresses.  This is useful on mailers that
          are going to pass addresses to a shell that  might
          interpret angle brackets as I/O redirection.  How-
          ever, it does  not  protect  against  other  shell
          metacharacters.  Therefore, passing addresses to a
          shell should not be considered secure.

      D*  This mailer wants a "Date:" header line.

      e   This mailer is expensive to connect to, so try  to
          avoid  connecting  normally; any necessary connec-
          tion will occur during  a  queue  run.   See  also
          option HoldExpensive.

      E   Escape lines beginning with "From " in the message
          with a `>' sign.

      f   The mailer wants a -f from flag, but only if  this
          is  a  network forward operation (i.e., the mailer
          will give an error if the executing user does  not
          have special permissions).

      F*  This mailer wants a "From:" header line.

      g   Normally,   sendmail  sends  internally  generated
          email (e.g., error messages) using the null return
          address  as  required  by RFC 1123.  However, some
          mailers don't accept a null  return  address.   If
          necessary, you can set the g flag to prevent send-
          mail from obeying the  standards;  error  messages
          will  be sent as from the MAILER-DAEMON (actually,
          the value of the $n macro).












SMM:08-82          Sendmail Installation and Operation Guide


      h   Upper case should be preserved in host names  (the
          $@  portion  of  the  mailer triplet resolved from
          ruleset 0) for this mailer.

      i   Do User  Database  rewriting  on  envelope  sender
          address.

      I   This mailer will be speaking SMTP to another send-
          mail -- as such it can use special  protocol  fea-
          tures.   This  flag  should not be used except for
          debugging purposes because it uses  VERB  as  SMTP
          command.

      j   Do  User  Database rewriting on recipients as well
          as senders.

      k   Normally when sendmail  connects  to  a  host  via
          SMTP, it checks to make sure that this isn't acci-
          dently the same host name as might happen if send-
          mail  is  misconfigured  or if a long-haul network
          interface is set in loopback mode.  This flag dis-
          ables  the loopback check.  It should only be used
          under very unusual circumstances.

      K   Currently unimplemented.  Reserved for chunking.

      l   This mailer is local (i.e., final delivery will be
          performed).

      L   Limit  the  line  lengths as specified in RFC 821.
          This deprecated option should be replaced  by  the
          L=  mail declaration.  For historic reasons, the L
          flag also sets the 7 flag.

      m   This mailer can send to multiple users on the same
          host  in  one transaction.  When a $u macro occurs
          in the argv part of the  mailer  definition,  that
          field will be repeated as necessary for all quali-
          fying users.  Removing this flag can defeat dupli-
          cate supression on a remote site as each recipient
          is sent in a separate transaction.

      M*  This mailer wants a "Message-Id:" header line.

      n   Do not insert a  UNIX-style  "From"  line  on  the
          front of the message.

      o   Always  run as the owner of the recipient mailbox.
          Normally sendmail runs as the sender  for  locally
          generated  mail or as "daemon" (actually, the user
          specified in the u option) when delivering network
          mail.   The  normal  behavior  is required by most
          local mailers, which will not allow  the  envelope










Sendmail Installation and Operation Guide          SMM:08-83


          sender address to be set unless the mailer is run-
          ning as daemon.  This flag is  ignored  if  the  S
          flag is set.

      p   Use  the route-addr style reverse-path in the SMTP
          "MAIL FROM:" command rather than just  the  return
          address; although this is required in RFC 821 sec-
          tion 3.1, many hosts do not process  reverse-paths
          properly.   Reverse-paths  are officially discour-
          aged by RFC 1123.

      P*  This mailer wants a "Return-Path:" line.

      q   When an address that resolves to  this  mailer  is
          verified   (SMTP   VRFY   command),  generate  250
          responses instead of  252  responses.   This  will
          imply that the address is local.

      r   Same as f, but sends a -r flag.

      R   Open   SMTP  connections  from  a  "secure"  port.
          Secure ports aren't (secure, that  is)  except  on
          UNIX  machines,  so  it  is unclear that this adds
          anything.  sendmail must be running as root to  be
          able to use this flag.

      s   Strip  quote  characters  ("  and  \)  off  of the
          address before calling the mailer.

      S   Don't reset the userid before calling the  mailer.
          This  would  be used in a secure environment where
          sendmail ran as root.  This could be used to avoid
          forged  addresses.  If the U= field is also speci-
          fied, this flag causes the effective user id to be
          set to that user.

      u   Upper  case  should be preserved in user names for
          this mailer.  Standards  require  preservation  of
          case  in  the  local part of addresses, except for
          those  address  for  which  your  system   accepts
          responsibility.   RFC 2142 provides a long list of
          addresses which should be  case  insensitive.   If
          you  use this flag, you may be violating RFC 2142.
          Note that postmaster is always treated as  a  case
          insensitive address regardless of this flag.

      U   This mailer wants UUCP-style "From" lines with the
          ugly "remote from <host>" on the end.

      w   The  user  must  have  a  valid  account  on  this
          machine, i.e., getpwnam must succeed.  If not, the
          mail is bounced.   See  also  the  MailBoxDatabase
          option.    This  is  required  to  get  ".forward"










SMM:08-84          Sendmail Installation and Operation Guide


          capability.

      x*  This mailer wants a "Full-Name:" header line.

      X   This mailer wants to use the hidden dot  algorithm
          as  specified  in  RFC  821;  basically,  any line
          beginning with  a  dot  will  have  an  extra  dot
          prepended (to be stripped at the other end).  This
          insures that lines in the message containing a dot
          will not terminate the message prematurely.

      z   Run  Local  Mail  Transfer Protocol (LMTP) between
          sendmail and the local mailer.  This is a  variant
          on  SMTP  defined in RFC 2033 that is specifically
          designed for delivery to a local mailbox.

      Z   Apply DialDelay (if set) to this mailer.

      0   Don't look  up  MX  records  for  hosts  sent  via
          SMTP/LMTP.  Do not apply FallbackMXhost either.

      1   Don't  send null characters ('\0') to this mailer.

      2   Don't use ESMTP even if offered;  this  is  useful
          for  broken  systems  that offer ESMTP but fail on
          EHLO (without recovering when HELO is tried next).

      3   Extend  the  list  of  characters converted to =XX
          notation when converting  to  Quoted-Printable  to
          include those that don't map cleanly between ASCII
          and EBCDIC.  Useful if you have IBM mainframes  on
          site.

      5   If no aliases are found for this address, pass the
          address through ruleset 5 for  possible  alternate
          resolution.   This is intended to forward the mail
          to an alternate delivery spot.

      6   Strip headers to seven bits.

      7   Strip all output  to  seven  bits.   This  is  the
          default  if the L flag is set.  Note that clearing
          this option is not sufficient to  get  full  eight
          bit data passed through sendmail.  If the 7 option
          is set, this is essentially always set, since  the
          eighth  bit was stripped on input.  Note that this
          option will only impact messages that didn't  have
          8->7 bit MIME conversions performed.

      8   If set, it is acceptable to send eight bit data to
          this mailer; the usual attempt to do 8->7 bit MIME
          conversions will be bypassed.











Sendmail Installation and Operation Guide          SMM:08-85


      9   If  set,  do  limited  7->8  bit MIME conversions.
          These conversions are limited to text/plain  data.

      :   Check  addresses to see if they begin ":include:";
          if  they  do,  convert  them  to  the  "*include*"
          mailer.

      |   Check  addresses  to see if they begin with a `|';
          if they do, convert them to the "prog" mailer.

      /   Check addresses to see if they begin with  a  `/';
          if they do, convert them to the "*file*" mailer.

      @   Look up addresses in the user database.

      %   Do  not attempt delivery on initial recipient of a
          message or on queue runs unless the queued message
          is selected using one of the -qI/-qR/-qS queue run
          modifiers or an ETRN request.

           Configuration files prior to level 6  assume  the
      `A',  `w',  `5', `:', `|', `/', and `@' options on the
      mailer named "local".

           The mailer with the special name "error"  can  be
      used  to  generate  a user error.  The (optional) host
      field is an exit status to be returned, and  the  user
      field is a message to be printed.  The exit status may
      be numeric or one of the values USAGE, NOUSER, NOHOST,
      UNAVAILABLE,  SOFTWARE,  TEMPFAIL, PROTOCOL, or CONFIG
      to return the  corresponding  EX_  exit  code,  or  an
      enhanced error code as described in RFC 1893, Enhanced
      Mail System Status Codes.  For example, the entry:

          $#error $@ NOHOST $: Host unknown in this domain

      on the RHS of a rule will cause the specified error to
      be  generated and the "Host unknown" exit status to be
      returned if the LHS  matches.   This  mailer  is  only
      functional  in  rulesets  0,  5, or one of the check_*
      rulesets.

           The mailer with the special name "discard" causes
      any  mail  sent  to  it  to be discarded but otherwise
      treated as  though  it  were  successfully  delivered.
      This  mailer  cannot be used in ruleset 0, only in the
      various address checking rulesets.

           The mailer named "local" must be defined in every
      configuration  file.   This  is  used to deliver local
      mail, and is treated specially in several ways.  Addi-
      tionally,  three other mailers named "prog", "*file*",
      and "*include*" may be defined to tune the delivery of










SMM:08-86          Sendmail Installation and Operation Guide


      messages  to  programs,  files,  and  :include:  lists
      respectively.  They default to:

          Mprog, P=/bin/sh, F=lsoDq9, T=DNS/RFC822/X-Unix, A=sh -c $u
          M*file*, P=[FILE], F=lsDFMPEouq9, T=DNS/RFC822/X-Unix, A=FILE $u
          M*include*, P=/dev/null, F=su, A=INCLUDE $u


           Builtin pathnames are [FILE] and [IPC], the  for-
      mer  is  used  for  delivery  to files, the latter for
      delivery via interprocess communication.  For  mailers
      that  use  [IPC]  as pathname the argument vector (A=)
      must start with TCP or FILE for delivery via a TCP  or
      a  Unix  domain  socket.   If  TCP is used, the second
      argument must be the name  of  the  host  to  contact.
      Optionally  a  third argument can be used to specify a
      port, the default is smtp (port 25).  If FILE is used,
      the  second  argument  must  be  the  name of the Unix
      domain socket.

           If the argument vector does not contain  $u  then
      sendmail will speak SMTP (or LMTP if the mailer flag z
      is specified) to the mailer.

           If no Eol field is defined, then the  default  is
      "\r\n" for SMTP mailers and "\n" of others.

           The  Sender  and  Recipient  rewriting  sets  may
      either be a simple ruleset id or may be two ids  sepa-
      rated  by  a  slash; if so, the first rewriting set is
      applied  to  envelope  addresses  and  the  second  is
      applied  to  headers.   Setting any value to zero dis-
      ables corresponding mailer-specific rewriting.

           The Directory is actually a colon-separated  path
      of  directories  to  try.  For example, the definition
      "D=$z:/" first tries to  execute  in  the  recipient's
      home  directory; if that is not available, it tries to
      execute in  the  root  of  the  filesystem.   This  is
      intended  to  be used only on the "prog" mailer, since
      some shells (such as csh) refuse to  execute  if  they
      cannot  read  the  current directory.  Since the queue
      directory is not  normally  readable  by  unprivileged
      users csh scripts as recipients can fail.

           The  Userid  specifies the default user and group
      id  to  run  as,  overriding  the  DefaultUser  option
      (q.v.).   If the S mailer flag is also specified, this
      user and group will be set as the  effective  uid  and
      gid  for the process.  This may be given as user:group
      to set both the user and group id; either  may  be  an
      integer  or  a  symbolic  name  to be looked up in the
      passwd  and  group  files  respectively.   If  only  a










Sendmail Installation and Operation Guide          SMM:08-87


      symbolic  user  name is specified, the group id in the
      passwd file for that user is used as the group id.

           The Charset field is used when converting a  mes-
      sage  to  MIME;  this is the character set used in the
      Content-Type:  header.   If  this  is  not  set,   the
      DefaultCharset option is used, and if that is not set,
      the value "unknown-8bit" is used.  WARNING: this field
      applies  to  the  sender's mailer, not the recipient's
      mailer.  For example, if the envelope  sender  address
      lists  an address on the local network and the recipi-
      ent is on an external network, the character set  will
      be  set  from the Charset= field for the local network
      mailer, not that of the external network mailer.

           The Type= field sets the type information used in
      MIME  error  messages  as  defined by RFC 1894.  It is
      actually three values separated by slashes:  the  MTA-
      type  (that  is,  the  description  of  how  hosts are
      named), the address type (the  description  of  e-mail
      addresses),  and  the diagnostic type (the description
      of error diagnostic codes).  Each of these must  be  a
      registered  value  or begin with "X-".  The default is
      "dns/rfc822/smtp".

           The m= field specifies the maximum number of mes-
      sages  to  attempt to deliver on a single SMTP or LMTP
      connection.  The default is infinite.

           The r= field  specifies  the  maximum  number  of
      recipients to attempt to deliver in a single envelope.
      It defaults to 100.

           The /= field specifies a new root  directory  for
      the  mailer.   The  path  is  macro  expanded and then
      passed to the "chroot" system call.  The  root  direc-
      tory  is  changed  before  the Directory field is con-
      sulted or the uid is changed.

           The Wait= field specifies  the  maximum  time  to
      wait  for  the mailer to return after sending all data
      to it.  This applies to mailers that have been  forked
      by sendmail.

           The Queuegroup= field specifies the default queue
      group in which received mail should be  queued.   This
      can  be overridden by other means as explained in sec-
      tion ``Queue Groups and Queue Directories''.

   5.5.  H -- Define Header

           The format of  the  header  lines  that  sendmail
      inserts  into  the  message are defined by the H line.










SMM:08-88          Sendmail Installation and Operation Guide


      The syntax of this line is one of the following:

          Hhname: htemplate


          H[?mflags?]hname: htemplate


          H[?${macro}?]hname: htemplate

      Continuation lines in this spec are reflected directly
      into  the  outgoing  message.  The htemplate is macro-
      expanded before insertion into the  message.   If  the
      mflags  (surrounded  by question marks) are specified,
      at least one of the specified flags must be stated  in
      the  mailer definition for this header to be automati-
      cally output.  If a ${macro} (surrounded  by  question
      marks)  is specified, the header will be automatically
      output if the macro is set.   The  macro  may  be  set
      using  any  of the normal methods, including using the
      macro storage map in a ruleset.  If one of these head-
      ers  is  in  the  input  it is reflected to the output
      regardless of these flags or  macros.   Notice:  If  a
      ${macro} is used to set a header, then it is useful to
      add that macro  to  class  $={persistentMacros}  which
      consists  of  the  macros  that should be saved across
      queue runs.

           Some headers have special semantics that will  be
      described later.

           A  secondary  syntax allows validation of headers
      as they are being read.  To enable validation, use:

          HHeader: $>Ruleset
          HHeader: $>+Ruleset

      The indicated Ruleset  is  called  for  the  specified
      Header,  and  can return $#error to reject the message
      or $#discard to discard the message (as with the other
      check_*  rulesets).   The  ruleset receives the header
      field-body as argument, i.e., not  the  header  field-
      name;  see  also  ${hdr_name}  and ${currHeader}.  The
      header is treated as a structured field, that is, text
      in  parentheses  is  deleted before processing, unless
      the second form $>+ is used.  Note: only  one  ruleset
      can   be  associated  with  a  header;  sendmail  will
      silently ignore multiple entries.

           For example, the configuration lines:













Sendmail Installation and Operation Guide          SMM:08-89


          HMessage-Id: $>CheckMessageId

          SCheckMessageId
          R< $+ @ $+  >$@ OK
          R$*       $#error $: Illegal Message-Id header

      would refuse any message that had a Message-Id: header
      of any of the following forms:

          Message-Id: <>
          Message-Id: some text
          Message-Id: <legal text@domain> extra crud

      A  default  ruleset  that  is called for headers which
      don't have a specific ruleset defined for them can  be
      specified by:

          H*: $>Ruleset

      or

          H*: $>+Ruleset


   5.6.  O -- Set Option

           There  are a number of global options that can be
      set from a configuration  file.   Options  are  repre-
      sented  by  full words; some are also representable as
      single characters for back compatibility.  The  syntax
      of this line is:

          O  option=value

      This  sets option option to be value.  Note that there
      must be a space between the letter `O' and the name of
      the option.  An older version is:

          Oovalue

      where  the  option o is a single character.  Depending
      on the option, value may be a string,  an  integer,  a
      boolean  (with legal values "t", "T", "f", or "F"; the
      default is TRUE), or a time interval.

           All filenames used in options should be  absolute
      paths,  i.e.,  starting  with '/'.  Relative filenames
      most likely cause surprises during  operation  (unless
      otherwise noted).

           The  options supported (with the old, one charac-
      ter names in brackets) are:











SMM:08-90          Sendmail Installation and Operation Guide


      AliasFile=spec, spec, ...
                [A] Specify possible  alias  file(s).   Each
                spec should be in the format ``class: info''
                where class: is  optional  and  defaults  to
                ``implicit''.   Note  that  info is required
                for all  classes  except  "ldap".   For  the
                "ldap"  class,  if  info is not specified, a
                default info value is used as follows:

                    -k (&(objectClass=sendmailMTAAliasObject)
                         (sendmailMTAAliasName=aliases)
                         (|(sendmailMTACluster=${sendmailMTACluster})
                           (sendmailMTAHost=$j))
                         (sendmailMTAKey=%0))
                    -v sendmailMTAAliasValue

                Depending on how sendmail is compiled, valid
                classes  are  "implicit"  (search  through a
                compiled-in list of alias  file  types,  for
                back  compatibility),  "hash"  (if  NEWDB is
                specified), "btree" (if NEWDB is specified),
                "dbm" (if NDBM is specified), "stab" (inter-
                nal symbol table -- not normally used unless
                you   have   no   other   database  lookup),
                "sequence" (use a sequence  of  maps  previ-
                ously declared), "ldap" (if LDAPMAP is spec-
                ified), or "nis" (if NIS is specified).   If
                a  list  of  specs  are  provided,  sendmail
                searches them in order.

      AliasWait=timeout
                [a]  If  set,  wait  up  to  timeout  (units
                default  to  minutes)  for an "@:@" entry to
                exist in the alias database before  starting
                up.   If  it  does not appear in the timeout
                interval issue a warning.

      AllowBogusHELO
                [no short name] If set, allow HELO SMTP com-
                mands  that don't include a host name.  Set-
                ting this violates RFC 1123  section  5.2.5,
                but  is  necessary to interoperate with sev-
                eral SMTP clients.  If there is a value,  it
                is still checked for legitimacy.

      AuthMaxBits=N
                [no short name] Limit the maximum encryption
                strength for the security layer in SMTP AUTH
                (SASL).  Default  is  essentially unlimited.
                This allows to turn off  additional  encryp-
                tion in SASL if STARTTLS is already encrypt-
                ing the communication, because the  existing
                encryption  strength  is  taken into account










Sendmail Installation and Operation Guide          SMM:08-91


                when choosing an algorithm for the  security
                layer.  For example, if STARTTLS is used and
                the symmetric cipher is 3DES, then  the  the
                keylength  (in  bits) is 168.  Hence setting
                AuthMaxBits to 168 will disable any  encryp-
                tion in SASL.

      AuthMechanisms
                [no short name] List of authentication mech-
                anisms for AUTH (separated by spaces).   The
                advertised list of authentication mechanisms
                will be the intersection of  this  list  and
                the  list  of available mechanisms as deter-
                mined by the Cyrus SASL library.  If  START-
                TLS  is  active,  EXTERNAL  will be added to
                this list.   In  that  case,  the  value  of
                {cert_subject} is used as authentication id.

      AuthOptions
                [no short name] List  of  options  for  SMTP
                AUTH  consisting  of  single characters with
                intervening white space or commas.

                    A   Use the AUTH= parameter for the MAIL FROM
                        command only when authentication succeeded.
                        This can be used as a workaround for broken
                        MTAs that do not implement RFC 2554 correctly.
                    a   protection from active (non-dictionary) attacks
                        during authentication exchange.
                    c   require mechanisms which pass client credentials,
                        and allow mechanisms which can pass credentials
                        to do so.
                    d   don't permit mechanisms susceptible to passive
                        dictionary attack.
                    f   require forward secrecy between sessions
                        (breaking one won't help break next).
                    p   don't permit mechanisms susceptible to simple
                        passive attack (e.g., PLAIN, LOGIN).
                    y   don't permit mechanisms that allow anonymous login.

                The first option applies to  sendmail  as  a
                client, the others to a server.  Example:

                    O AuthOptions=p,y

                would  disallow  ANONYMOUS as AUTH mechanism
                and would allow PLAIN  only  if  a  security
                layer   (e.g.,   provided  by  STARTTLS)  is
                already active.  The options 'a', 'c',  'd',
                'f', 'p', and 'y' refer to properties of the
                selected SASL mechanisms.   Explanations  of
                these  properties  can be found in the Cyrus
                SASL documentation.










SMM:08-92          Sendmail Installation and Operation Guide


      BadRcptThrottle=N
                [no short name] If set  and  more  than  the
                specified  number  of recipients in a single
                SMTP envelope are rejected,  sleep  for  one
                second after each rejected RCPT command.

      BlankSub=c
                [B]  Set the blank substitution character to
                c.   Unquoted  spaces   in   addresses   are
                replaced  by  this  character.   Defaults to
                space (i.e., no change is made).

      CACERTPath
                [no short name] Path to directory with  cer-
                tificates  of CAs.  This directory directory
                must contain the hashes of each CA  certifi-
                cate as filenames (or as links to them).

      CACERTFile
                [no  short name] File containing one or more
                CA certificates; see section about  STARTTLS
                for more information.

      CheckAliases
                [n]   Validate   the  RHS  of  aliases  when
                rebuilding the alias database.

      CheckpointInterval=N
                [C] Checkpoints the queue every  N  (default
                10)  addresses sent.  If your system crashes
                during delivery to a large list,  this  pre-
                vents  retransmission  to any but the last N
                recipients.

      ClassFactor=fact
                [z] The indicated factor  is  multiplied  by
                the  message class (determined by the Prece-
                dence: field in the user header  and  the  P
                lines  in  the  configuration file) and sub-
                tracted from the priority.   Thus,  messages
                with  a  higher  Priority:  will be favored.
                Defaults to 1800.

      ClientCertFile
                [no short name] File containing the certifi-
                cate  of  the client, i.e., this certificate
                is used when sendmail acts  as  client  (for
                STARTTLS).

      ClientKeyFile
                [no  short name] File containing the private
                key belonging to the client certificate (for
                STARTTLS if sendmail runs as client).










Sendmail Installation and Operation Guide          SMM:08-93


      ClientPortOptions=options
                [O]  Set  client  SMTP options.  The options
                are key=value  pairs  separated  by  commas.
                Known keys are:

                    Port      Name/number of source port for connection (defaults to any free port)
                    Addr      Address mask (defaults INADDR_ANY)
                    Family    Address family (defaults to INET)
                    SndBufSizeSize of TCP send buffer
                    RcvBufSizeSize of TCP receive buffer
                    Modifier  Options (flags) for the daemon

                The Address mask may be a numeric address in
                dot notation or a  network  name.   Modifier
                can be the following character:

                    h         use name of interface for HELO command
                    A         don't use AUTH when sending e-mail
                    S         don't use STARTTLS when sending e-mail

                If  ``h''  is set, the name corresponding to
                the outgoing interface address (whether cho-
                sen  via  the  Connection  parameter  or the
                default) is used for the HELO/EHLO  command.
                However,  the  name  must  not  start with a
                square bracket and it must contain at  least
                one  dot.  This is a simple test whether the
                name is not an IP address (in square  brack-
                ets)  but  a  qualified hostname.  Note that
                multiple  ClientPortOptions   settings   are
                allowed  in  order to give settings for each
                protocol family (e.g., one  for  Family=inet
                and  one  for  Family=inet6).  A restriction
                placed on one family only  affects  outgoing
                connections on that particular family.

      ColonOkInAddr
                [no  short  name] If set, colons are accept-
                able    in    e-mail    addresses     (e.g.,
                "host:user").   If  not set, colons indicate
                the beginning of a RFC 822  group  construct
                ("groupname:   member1,  member2,  ...  mem-
                berN;").  Doubled colons are always  accept-
                able  ("nodename::user")  and  proper route-
                addr       nesting       is       understood
                ("<@relay:user@host>").   Furthermore,  this
                option defaults on if the configuration ver-
                sion level is less than 6 (for back compati-
                bility).  However, it must be off  for  full
                compatibility with RFC 822.

      ConnectionCacheSize=N
                [k]  The  maximum number of open connections










SMM:08-94          Sendmail Installation and Operation Guide


                that will be cached at a time.  The  default
                is  one.   This  delays  closing the current
                connection until either this  invocation  of
                sendmail needs to connect to another host or
                it terminates.  Setting it to zero  defaults
                to  the  old  behavior, that is, connections
                are closed immediately.  Since this consumes
                file   descriptors,   the  connection  cache
                should be kept small: 4 is probably a  prac-
                tical maximum.

      ConnectionCacheTimeout=timeout
                [K] The maximum amount of time a cached con-
                nection will be permitted  to  idle  without
                activity.   If  this  time  is exceeded, the
                connection  is  immediately  closed.    This
                value  should  be small (on the order of ten
                minutes).  Before  sendmail  uses  a  cached
                connection,  it  always sends a RSET command
                to check the connection; if this  fails,  it
                reopens the connection.  This keeps your end
                from failing if the  other  end  times  out.
                The  point  of  this  option is to be a good
                network neighbor and avoid using  up  exces-
                sive   resources  on  the  other  end.   The
                default is five minutes.

      ConnectOnlyTo=address
                [no short name] This can be used to override
                the  connection  address  (for  testing pur-
                poses).

      ConnectionRateThrottle=N
                [no short name] If set to a positive  value,
                allow no more than N incoming connections in
                a one second period  per  daemon.   This  is
                intended  to flatten out peaks and allow the
                load average checking to cut  in.   Defaults
                to zero (no limits).

      ControlSocketName=name
                [no  short  name] Name of the control socket
                for daemon management.  A  running  sendmail
                daemon  can be controlled through this named
                socket.   Available  commands   are:   help,
                restart,  shutdown,  and status.  The status
                command returns the current number of daemon
                children, the maximum number of daemon chil-
                dren, the free disk space (in blocks) of the
                queue directory, and the load average of the
                machine expressed as  an  integer.   If  not
                set,  no  control  socket will be available.
                Solaris and pre-4.4BSD kernel  users  should










Sendmail Installation and Operation Guide          SMM:08-95


                see the note in sendmail/README .

      DHParameters
                File  with DH parameters for STARTTLS.  This
                is only required if a ciphersuite containing
                DSA/DH  is  used.   This  is only for people
                with a good knowledge of TLS, all others can
                ignore this option.

      DaemonPortOptions=options
                [O]  Set server SMTP options.  Each instance
                of DaemonPortOptions leads to an  additional
                incoming  socket.  The options are key=value
                pairs.  Known keys are:

                    Name      User-definable name for the daemon (defaults to "Daemon#")
                    Port      Name/number of listening port (defaults to "smtp")
                    Addr      Address mask (defaults INADDR_ANY)
                    Family    Address family (defaults to INET)
                    Listen    Size of listen queue (defaults to 10)
                    Modifier  Options (flags) for the daemon
                    SndBufSizeSize of TCP send buffer
                    RcvBufSizeSize of TCP receive buffer

                The Name field is used  for  error  messages
                and  logging.   The  Address  mask  may be a
                numeric address in dot notation or a network
                name.   The  Family  key  defaults  to  INET
                (IPv4).  IPv6 users who wish to also  accept
                IPv6  connections should add additional Fam-
                ily=inet6 DaemonPortOptions lines.  Modifier
                can  be  a sequence (without any delimiters)
                of the following characters:

                    a         always require authentication
                    b         bind to interface through which mail has been received
                    c         perform hostname canonification (.cf)
                    f         require fully qualified hostname (.cf)
                    u         allow unqualified addresses (.cf)
                    A         disable AUTH (overrides 'a' modifier)
                    C         don't perform hostname canonification
                    E         disallow ETRN (see RFC 2476)
                    O         optional; if opening the socket fails ignore it
                    S         don't offer STARTTLS

                That is, one way to specify a  message  sub-
                mission  agent  (MSA)  that  always requires
                authentication is:

                    O DaemonPortOptions=Name=MSA, Port=587, M=Ea

                The modifiers that are marked  with  "(.cf)"
                have    only    effect   in   the   standard










SMM:08-96          Sendmail Installation and Operation Guide


                configuration file, in which they are avail-
                able  via  ${daemon_flags}.   Notice: Do not
                use the ``a'' modifier on a public  accessi-
                ble  MTA!   It should only be used for a MSA
                that is accessed  by  authorized  users  for
                initial mail submission.  Users must authen-
                ticate to use a MSA which  has  this  option
                turned  on.   The  flags ``c'' and ``C'' can
                change the default for hostname  canonifica-
                tion in the sendmail.cf file.  See the rele-
                vant documentation for  FEATURE(nocanonify).
                The  modifier  ``f''  disallows addresses of
                the form user@host unless they are submitted
                directly.  The flag ``u'' allows unqualified
                sender addresses, i.e., those without @host.
                ``b''  forces sendmail to bind to the inter-
                face  through  which  the  e-mail  has  been
                received for the outgoing connection.  WARN-
                ING: Use ``b'' only if outgoing mail can  be
                routed  through  the  incoming  connection's
                interface to its destination. No attempt  is
                made  to catch problems due to a misconfigu-
                ration of this parameter, use  it  only  for
                virtual hosting where each virtual interface
                can  connect  to  every  possible  location.
                This  will  also  override possible settings
                via ClientPortOptions.  Note, sendmail  will
                listen on a new socket for each occurence of
                the DaemonPortOptions option in a configura-
                tion  file.  The modifier ``O'' causes send-
                mail to ignore  a  socket  if  it  can't  be
                opened.   This  applies to failures from the
                socket(2) and bind(2) calls.

      DefaultAuthInfo
                [no  short  name]  Filename  that   contains
                default  authentication information for out-
                going connections. This  file  must  contain
                the user id, the authorization id, the pass-
                word (plain text), the realm and the list of
                mechanisms to use on separate lines and must
                be readable by root (or  the  trusted  user)
                only.  If no realm is specified, $j is used.
                If no mechanisms  are  specified,  the  list
                given  by  AuthMechanisms  is used.  Notice:
                this  option  is  deprecated  and  will   be
                removed  in  future  versions.  Moreover, it
                doesn't work for the MSP since it can't read
                the  file (the file must not be group/world-
                readable otherwise sendmail will  complain).
                Use  the authinfo ruleset instead which pro-
                vides more control over  the  usage  of  the
                data anyway.










Sendmail Installation and Operation Guide          SMM:08-97


      DefaultCharSet=charset
                [no  short  name]  When  a  message that has
                8-bit characters but is not in  MIME  format
                is  converted  to MIME (see the EightBitMode
                option) a character set must be included  in
                the  Content-Type:  header.   This character
                set is normally set from the Charset=  field
                of  the  mailer  descriptor.  If that is not
                set, the value of this option is  used.   If
                this   option   is   not   set,   the  value
                "unknown-8bit" is used.

      DataFileBufferSize=threshold
                [no short name] Set the threshold, in bytes,
                before   a   memory-based  queue  data  file
                becomes disk-based.   The  default  is  4096
                bytes.

      DeadLetterDrop=file
                [no  short name] Defines the location of the
                system-wide dead.letter file, formerly hard-
                coded   to  /usr/tmp/dead.letter.   If  this
                option is not set  (the  default),  sendmail
                will  not  attempt  to save to a system-wide
                dead.letter file  in  the  event  it  cannot
                bounce  the  mail to the user or postmaster.
                Instead, it will rename the qf  file  as  it
                has  in  the  past when the dead.letter file
                could not be opened.

      DefaultUser=user:group
                [u] Set the default userid  for  mailers  to
                user:group.  If group is omitted and user is
                a user name (as opposed to  a  numeric  user
                id)   the   default   group  listed  in  the
                /etc/passwd file for that user  is  used  as
                the  default group.  Both user and group may
                be numeric.  Mailers without the S  flag  in
                the mailer definition will run as this user.
                Defaults to 1:1.   The  value  can  also  be
                given as a symbolic user name.19

      DelayLA=LA
                [no short name] When the system load average
                exceeds LA, sendmail will sleep for one sec-
                ond on most SMTP commands and before accept-
                ing connections.

____________________
   19The old g option has been combined into the DefaultUser
option.












SMM:08-98          Sendmail Installation and Operation Guide


      DeliverByMin=time
                [0]  Set  minimum  time  for Deliver By SMTP
                Service Extension (RFC 2852).  If 0, no time
                is  listed, if less than 0, the extension is
                not offered, if greater than 0, it is listed
                as  minimum time for the EHLO keyword DELIV-
                ERBY.

      DeliveryMode=x
                [d] Deliver in mode x.  Legal modes are:

                    i   Deliver interactively (synchronously)
                    b   Deliver in background (asynchronously)
                    q   Just queue the message (deliver during queue run)
                    d   Defer delivery and all map lookups (deliver during queue run)

                Defaults to ``b'' if no option is specified,
                ``i''  if it is specified but given no argu-
                ment  (i.e.,   ``Od''   is   equivalent   to
                ``Odi'').   The  -v  command  line flag sets
                this to i.

      DialDelay=sleeptime
                [no short name] Dial-on-demand network  con-
                nections can see timeouts if a connection is
                opened before the call is set up.   If  this
                is set to an interval and a connection times
                out on the first connection being  attempted
                sendmail  will sleep for this amount of time
                and try again.  This should give your system
                time  to  establish  the  connection to your
                service provider.  Units default to seconds,
                so  "DialDelay=5"  uses a five second delay.
                Defaults to zero  (no  retry).   This  delay
                only  applies  to  mailers  which have the Z
                flag set.

      DirectSubmissionModifiers=modifiers
                Defines ${daemon_flags} for direct  (command
                line)   submissions.   If  not  set,  ${dae-
                mon_flags} is either "CC f" if the option -G
                is  used or "c u" otherwise.  Note that only
                the the "CC", "c", "f", and  "u"  flags  are
                checked.

      DontBlameSendmail=option,option,...
                [no  short  name] In order to avoid possible
                cracking  attempts  caused  by  world-   and
                group-writable  files and directories, send-
                mail does  paranoid  checking  when  opening
                most of its support files.  If for some rea-
                son you absolutely must run with, for  exam-
                ple,  a  group-writable /etc directory, then










Sendmail Installation and Operation Guide          SMM:08-99


                you will have to turn off this checking  (at
                the cost of making your system more vulnera-
                ble to attack).  The possible arguments have
                been  described  earlier.   The  details  of
                these flags are  described  above.   Use  of
                this option is not recommended.

      DontExpandCnames
                [no  short  name] The standards say that all
                host addresses used in a mail  message  must
                be  fully  canonical.   For example, if your
                host is named "Cruft.Foo.ORG" and  also  has
                an  alias  of "FTP.Foo.ORG", the former name
                must be used at all times.  This is enforced
                during  host  name canonification ($[ ... $]
                lookups).  If this option is set, the proto-
                cols  are  ignored  and the "wrong" thing is
                done.  However, the IETF  is  moving  toward
                changing  this standard, so the behavior may
                become acceptable.  Please note  that  hosts
                downstream  may still rewrite the address to
                be the true canonical name however.

      DontInitGroups
                [no short name] If set, sendmail will  avoid
                using  the  initgroups(3)  call.  If you are
                running NIS, this causes a  sequential  scan
                of  the  groups.byname  map, which can cause
                your NIS server to be badly overloaded in  a
                large  domain.  The cost of this is that the
                only group found for  users  will  be  their
                primary  group  (the  one  in  the  password
                file), which will make file  access  permis-
                sions  somewhat  more  restrictive.   Has no
                effect on  systems  that  don't  have  group
                lists.

      DontProbeInterfaces
                [no  short name] Sendmail normally finds the
                names  of  all  interfaces  active  on  your
                machine  when  it  starts  up and adds their
                name to the $=w class of known host aliases.
                If you have a large number of virtual inter-
                faces or if your  DNS  inverse  lookups  are
                slow  this  can  be  time  consuming.   This
                option turns off that probing.  However, you
                will need to be certain to include all vari-
                ant names in the $=w  class  by  some  other
                mechanism.   If  set  to  loopback, loopback
                interfaces (e.g., lo0) will not be probed.

      DontPruneRoutes
                [R] Normally, sendmail  tries  to  eliminate










SMM:08-100         Sendmail Installation and Operation Guide


                any unnecessary explicit routes when sending
                an error message (as discussed in RFC 1123 S
                5.2.6).   For example, when sending an error
                message to

                    <@known1,@known2,@known3:user@unknown>

                sendmail     will     strip     off      the
                "@known1,@known2" in order to make the route
                as direct as possible.  However,  if  the  R
                option  is  set,  this will be disabled, and
                the mail will be sent to the  first  address
                in  the  route,  even if later addresses are
                known.  This may be useful if you are caught
                behind a firewall.

      DoubleBounceAddress=error-address
                [no  short  name]  If  an  error occurs when
                sending an error  message,  send  the  error
                report  (termed a "double bounce" because it
                is an error "bounce" that occurs when trying
                to send another error "bounce") to the indi-
                cated  address.   The   address   is   macro
                expanded  at  the  time of delivery.  If not
                set, defaults to "postmaster".  If set to an
                empty string, double bounces are dropped.

      EightBitMode=action
                [8]  Set  handling of eight-bit data.  There
                are  two  kinds  of  eight-bit  data:   that
                declared  as  such  using  the BODY=8BITMIME
                ESMTP declaration or the -B8BITMIME  command
                line  flag,  and undeclared 8-bit data, that
                is, input that  just  happens  to  be  eight
                bits.  There are three basic operations that
                can happen: undeclared  8-bit  data  can  be
                automatically  converted  to 8BITMIME, unde-
                clared 8-bit data can be passed as-is  with-
                out  conversion  to  MIME (``just send 8''),
                and declared 8-bit data can be converted  to
                7-bits  for  transmission  to a non-8BITMIME
                mailer.  The possible actions are:

                      s Reject undeclared 8-bit data (``strict'')
                      m Convert undeclared 8-bit data to MIME (``mime'')
                      p Pass undeclared 8-bit data (``pass'')

                In all cases properly declared 8BITMIME data
                will be converted to 7BIT as needed.

      ErrorHeader=file-or-message
                [E]  Prepend  error  messages with the indi-
                cated message.  If it begins with  a  slash,










Sendmail Installation and Operation Guide         SMM:08-101


                it  is  assumed to be the pathname of a file
                containing a message  (this  is  the  recom-
                mended setting).  Otherwise, it is a literal
                message.  The error file might  contain  the
                name,  email address, and/or phone number of
                a local postmaster who could provide  assis-
                tance  to end users.  If the option is miss-
                ing or null, or if it  names  a  file  which
                does  not exist or which is not readable, no
                message is printed.

      ErrorMode=x
                [e] Dispose of errors  using  mode  x.   The
                values for x are:

                    p   Print error messages (default)
                    q   No messages, just give exit status
                    m   Mail back errors
                    w   Write back errors (mail if user not logged in)
                    e   Mail back errors (when applicable) and give zero exit stat always

                Note that the last mode, "e", is for Berknet
                error processing and should not be  used  in
                normal circumstances.

      FallbackMXhost=fallbackhost
                [V] If specified, the fallbackhost acts like
                a very low priority MX on  every  host.   MX
                records  will  be  looked  up for this host,
                unless the  name  is  surrounded  by  square
                brackets.   This  is  intended to be used by
                sites with poor network connectivity.   Mes-
                sages  which are undeliverable due to tempo-
                rary address failures  (e.g.,  DNS  failure)
                also go to the FallbackMXhost.

      FastSplit [no  short  name]  If set to a value greater
                than zero (the  default  is  one),  it  sup-
                presses  the  MX  lookups  on addresses when
                they are initially  sorted,  i.e.,  for  the
                first   delivery   attempt.    This  usually
                results in faster envelope splitting  unless
                the  MX  records  are readily available in a
                local DNS cache.  To enforce initial sorting
                based  on  MX records set FastSplit to zero.
                If the mail is submitted directly  from  the
                command line, then the value also limits the
                number   of   processes   to   deliver   the
                envelopes;  if  more  envelopes  are created
                they are only queued up and  must  be  taken
                care  of  by a queue run.  Since the default
                submission method is via SMTP (either from a
                MUA  or via the MSP), the value of FastSplit










SMM:08-102         Sendmail Installation and Operation Guide


                is seldom used to limit the number  of  pro-
                cesses to deliver the envelopes.

      ForkEachJob
                [Y]  If  set,  deliver  each job that is run
                from the queue in a separate process.

      ForwardPath=path
                [J] Set the path for  searching  for  users'
                .forward  files.   The  default is "$z/.for-
                ward".  Some sites that use the  automounter
                may  prefer  to  change  this  to "/var/for-
                ward/$u" to search a file with the same name
                as  the  user in a system directory.  It can
                also be set to a sequence of paths separated
                by  colons; sendmail stops at the first file
                it can successfully and  safely  open.   For
                example,  "/var/forward/$u:$z/.forward" will
                search first  in  /var/forward/username  and
                then  in ~username/.forward (but only if the
                first file does not exist).

      HelpFile=file
                [H] Specify the help file for SMTP.   If  no
                file  name is specified, "helpfile" is used.

      HoldExpensive
                [c] If an outgoing mailer is marked as being
                expensive,  don't connect immediately.  This
                requires that queueing be compiled in, since
                it  will  depend  on  a queue run process to
                actually send the mail.

      HostsFile=path
                [no  short  name]  The  path  to  the  hosts
                database,   normally   "/etc/hosts".    This
                option is only consulted  when  sendmail  is
                canonifying  addresses,  and  then only when
                "files" is in  the  "hosts"  service  switch
                entry.   In  particular,  this file is never
                used when looking up host addresses; that is
                under  the  control of the system gethostby-
                name(3) routine.

      HostStatusDirectory=path
                [no short name] The  location  of  the  long
                term  host  status  information.   When set,
                information about the status of hosts (e.g.,
                host down or not accepting connections) will
                be shared between  all  sendmail  processes;
                normally,  this  information  is  only  held
                within a  single  queue  run.   This  option
                requires a connection cache of at least 1 to










Sendmail Installation and Operation Guide         SMM:08-103


                function.  If the option begins with a lead-
                ing  `/', it is an absolute pathname; other-
                wise, it  is  relative  to  the  mail  queue
                directory.   A  suggested  value  for  sites
                desiring persistent host status  is  ".host-
                stat"  (i.e.,  a  subdirectory  of the queue
                directory).

      IgnoreDots
                [i] Ignore dots in incoming messages.   This
                is always disabled (that is, dots are always
                accepted) when reading SMTP mail.

      InputMailFilters=name,name,...
                A comma  separated  list  of  filters  which
                determines which filters (see the "X -- Mail
                Filter (Milter)  Definitions"  section)  and
                the  invocation  sequence  are contacted for
                incoming SMTP messages.  If none are set, no
                filters will be contacted.

      LDAPDefaultSpec=spec
                [no  short name] Sets a default map specifi-
                cation for LDAP maps.  The value should only
                contain  LDAP  specific settings such as "-h
                host -p port -d bindDN".  The settings  will
                be  used  for all LDAP maps unless the indi-
                vidual map specification  overrides  a  set-
                ting.   This option should be set before any
                LDAP maps are defined.

      LogLevel=n
                [L] Set the log level to n.  Defaults to  9.

      Mxvalue   [no  long version] Set the macro x to value.
                This is intended only for use from the  com-
                mand line.  The -M flag is preferred.

      MailboxDatabase
                [no  short  name]  Type  of  lookup  to find
                information about local mailboxes,  defaults
                to  ``pw'' which uses getpwnam.  Other types
                can be introduced  by  adding  them  to  the
                source code, see libsm/mbdb.c for details.

      UseMSP    [no  short name] Use as mail submission pro-
                gram, i.e., allow group writable queue files
                if  the  group is the same as that of a set-
                group-ID  sendmail  binary.   See  the  file
                sendmail/SECURITY  in  the distribution tar-
                ball.












SMM:08-104         Sendmail Installation and Operation Guide


      MatchGECOS
                [G] Allow fuzzy matching on the GECOS field.
                If this flag is set, and the usual user name
                lookups fail (that is,  there  is  no  alias
                with   this  name  and  a  getpwnam  fails),
                sequentially search the password file for  a
                matching  entry  in  the  GECOS field.  This
                also requires that MATCHGECOS be  turned  on
                during compilation.  This option is not rec-
                ommended.

      MaxAliasRecursion=N
                [no short name] The maximum depth  of  alias
                recursion (default: 10).

      MaxDaemonChildren=N
                [no short name] If set, sendmail will refuse
                connections when it has more than N children
                processing  incoming mail or automatic queue
                runs.  This does not  limit  the  number  of
                outgoing  connections.  If not set, there is
                no limit to the number of children  --  that
                is, the system load averaging controls this.

      MaxHeadersLength=N
                [no short name] The maximum  length  of  the
                sum  of  all  headers.   This can be used to
                prevent a denial  of  service  attack.   The
                default is no limit.

      MaxHopCount=N
                [h]  The  maximum  hop count.  Messages that
                have been processed more than  N  times  are
                assumed  to  be  in a loop and are rejected.
                Defaults to 25.

      MaxMessageSize=N
                [no short name] Specify the maximum  message
                size  to  be  advertised  in  the ESMTP EHLO
                response.  Messages larger than this will be
                rejected.

      MaxMimeHeaderLength=N[/M]
                [no  short  name] Sets the maximum length of
                certain MIME header field values to N  char-
                acters.  These MIME header fields are deter-
                mined by being a member of class {checkMIME-
                TextHeaders},  which currently contains only
                the header Content-Description.  For some of
                these  headers  which  take  parameters, the
                maximum length of each parameter is set to M
                if  specified.   If /M is not specified, one
                half of N will be used.  By  default,  these










Sendmail Installation and Operation Guide         SMM:08-105


                values are 0, meaning no checks are done.

      MaxQueueChildren=N
                [no  short  name]  When set, this limits the
                number of concurrent queue runner  processes
                to  N.   This helps to control the amount of
                system resources used  when  processing  the
                queue.  When there are multiple queue groups
                defined and the total number of  queue  run-
                ners  for  these  queue  groups would exceed
                MaxQueueChildren then the queue groups  will
                not all run concurrently. That is, some por-
                tion of the queue groups  will  run  concur-
                rently  such  that MaxQueueChildren will not
                be  exceeded,  while  the  remaining   queue
                groups  will  be  run  later (in round robin
                order). See also MaxRunnersPerQueue and  the
                section  Queue  Group  Declaration.  Notice:
                sendmail does  not  count  individual  queue
                runners, but only sets of processes that act
                on a workgroup.  Hence the actual number  of
                queue  runners  may  be lower than the limit
                imposed by MaxQueueChildren.  This  discrep-
                ancy can be large if some queue runners have
                to wait for  a  slow  server  and  if  short
                intervals are used.

      MaxQueueRunSize=N
                [no  short  name] The maximum number of jobs
                that will be processed  in  a  single  queue
                run.   If  not set, there is no limit on the
                size.  If you have very large  queues  or  a
                very  short queue run interval this could be
                unstable.  However, since the first  N  jobs
                in  queue  directory  order  are run (rather
                than  the  N  highest  priority  jobs)  this
                should  be  set as high as possible to avoid
                "losing" jobs that happen to  fall  late  in
                the queue directory.

      MaxRecipientsPerMessage=N
                [no short name] The maximum number of recip-
                ients that will be accepted per  message  in
                an SMTP transaction.  Note: setting this too
                low can interfere  with  sending  mail  from
                MUAs  that  use SMTP for initial submission.
                If not set, there is no limit on the  number
                of recipients per envelope.

      MaxRunnersPerQueue=N
                [no  short name] This sets the default maxi-
                mum  number  of  queue  runners  for   queue
                groups.   Up to N queue runners will work in










SMM:08-106         Sendmail Installation and Operation Guide


                parallel on a queue group's messages.   This
                is  useful where the processing of a message
                in the queue might delay the  processing  of
                subsequent messages. Such a delay may be the
                result of non-erroneous situations such as a
                low bandwidth connection.  May be overridden
                on a per queue group basis  by  setting  the
                Runners  option; see the section Queue Group
                Declaration.  The default is 1 when not set.

      MeToo     [m] Send to me too, even if I am in an alias
                expansion.  This option  is  deprecated  and
                will be removed from a future version.

      Milter    [no  short  name]  This  option  has several
                sub(sub)options.  The names  of  the  subop-
                tions  are  separated by dots.  At the first
                level the following options are available:

                    LogLevel   Log level for input mail filter actions, defaults to LogLevel.
                    macros     Specifies list of macro to transmit to filters.
                               See list below.

                The ``macros'' option has the following sub-
                options  which  specify the list of macro to
                transmit to milters after  a  certain  event
                occurred.

                    connect   After session connection start
                    helo      After HELO command
                    envfrom   After MAIL FROM command
                    envrcpt   After RCPT TO command

                By  default  the  lists of macros are empty.
                Example:

                    O Milter.LogLevel=12
                    O Milter.macros.connect=j, _, {daemon_name}


      MinFreeBlocks=N
                [b] Insist on at least N blocks free on  the
                filesystem that holds the queue files before
                accepting  email  via  SMTP.   If  there  is
                insufficient  space  sendmail  gives  a  452
                response to the MAIL command.  This  invites
                the sender to try again later.

      MinQueueAge=age
                [no  short  name]  Don't  process any queued
                jobs that have been in the queue  less  than
                the   indicated   time  interval.   This  is
                intended to allow you to get  responsiveness










Sendmail Installation and Operation Guide         SMM:08-107


                by  processing  the  queue fairly frequently
                without thrashing your system by trying jobs
                too often.  The default units are minutes.

      MustQuoteChars=s
                [no  short name] Sets the list of characters
                that must be quoted if used in a  full  name
                that  is  in  the  phrase part of a ``phrase
                <address>'' syntax.  The default is  ``'.''.
                The   characters  ``@,;:\()[]''  are  always
                added to this list.

      NiceQueueRun
                [no short name] The priority of  queue  run-
                ners  (nice(3)).  This value must be greater
                or equal zero.

      NoRecipientAction
                [no short name] The action to take when  you
                receive  a message that has no valid recipi-
                ent headers (To:, Cc:, Bcc:, or  Apparently-
                To:  --  the last included for back compati-
                bility with old sendmails).  It can be  None
                to  pass  the  message  on unmodified, which
                violates the protocol, Add-To to add  a  To:
                header  with  any  recipients it can find in
                the envelope (which might expose Bcc: recip-
                ients),  Add-Apparently-To  to add an Appar-
                ently-To: header (this is only for back-com-
                patibility  and  is  officially deprecated),
                Add-To-Undisclosed  to  add  a  header  "To:
                undisclosed-recipients:;" to make the header
                legal without disclosing anything,  or  Add-
                Bcc to add an empty Bcc: header.

      OldStyleHeaders
                [o]  Assume  that  the headers may be in old
                format, i.e., spaces  delimit  names.   This
                actually  turns on an adaptive algorithm: if
                any  recipient  address  contains  a  comma,
                parenthesis,  or  angle  bracket, it will be
                assumed that commas already exist.  If  this
                flag  is  not on, only commas delimit names.
                Headers  are  always  output   with   commas
                between the names.  Defaults to off.

      OperatorChars=charlist
                [$o  macro]  The list of characters that are
                considered to be "operators", that is, char-
                acters  that  delimit  tokens.  All operator
                characters   are   tokens   by   themselves;
                sequences  of  non-operator  characters  are
                also   tokens.    White   space   characters










SMM:08-108         Sendmail Installation and Operation Guide


                separate  tokens  but  are  not tokens them-
                selves -- for example, "AAA.BBB"  has  three
                tokens,  but "AAA BBB" has two.  If not set,
                OperatorChars defaults to ".:@[]"; addition-
                ally,  the  characters  "()<>,;"  are always
                operators.  Note that OperatorChars must  be
                set  in  the  configuration  file before any
                rulesets.

      PidFile=filename
                [no short name] Filename of  the  pid  file.
                (default  is  _PATH_SENDMAILPID).  The file-
                name is macro-expanded before it is  opened.

      PostmasterCopy=postmaster
                [P] If set, copies of error messages will be
                sent to  the  named  postmaster.   Only  the
                header   of  the  failed  message  is  sent.
                Errors resulting from messages with a  nega-
                tive  precedence  will  not  be sent.  Since
                most errors are user problems, this is prob-
                ably  not  a  good  idea on large sites, and
                arguably contains all sorts of privacy  vio-
                lations,  but  it  seems  to be popular with
                certain  operating  systems  vendors.    The
                address  is  macro  expanded  at the time of
                delivery.  Defaults to no postmaster copies.

      PrivacyOptions=opt,opt,...
                [p] Set the privacy options.  ``Privacy'' is
                really a misnomer; many of these are just  a
                way  of  insisting  on stricter adherence to
                the  SMTP  protocol.   The  options  can  be
                selected from:

                    public         Allow open access
                    needmailhelo   Insist on HELO or EHLO command before MAIL
                    needexpnhelo   Insist on HELO or EHLO command before EXPN
                    noexpn         Disallow EXPN entirely, implies noverb.
                    needvrfyhelo   Insist on HELO or EHLO command before VRFY
                    novrfy         Disallow VRFY entirely
                    noetrn         Disallow ETRN entirely
                    noverb         Disallow VERB entirely
                    restrictmailq  Restrict mailq command
                    restrictqrun   Restrict -q command line flag
                    restrictexpand Restrict -bv and -v command line flags
                    noreceipts     Don't return success DSNs20
                    nobodyreturn   Don't return the body of a message with DSNs
                    goaway         Disallow essentially all SMTP status queries
                    authwarnings   Put X-Authentication-Warning: headers in messages
                                   and log warnings












Sendmail Installation and Operation Guide         SMM:08-109


                The  "goaway"  pseudo-flag  sets  all  flags
                except     "noreceipts",    "restrictmailq",
                "restrictqrun", "restrictexpand",  "noetrn",
                and "nobodyreturn".  If mailq is restricted,
                only people in the same group as  the  queue
                directory  can  print  the  queue.  If queue
                runs are restricted, only root and the owner
                of  the  queue  directory can run the queue.
                The "restrictexpand"  pseudo-flag  instructs
                sendmail  to  drop  privileges  when the -bv
                option is given by  users  who  are  neither
                root  nor  the  TrustedUser  so users cannot
                read private aliases, forwards, or :include:
                files.  It will add the "NonRootSafeAddr" to
                the "DontBlameSendmail"  option  to  prevent
                misleading unsafe address warnings.  It also
                overrides  the  -v  (verbose)  command  line
                option   to   prevent  information  leakage.
                Authentication Warnings add  warnings  about
                various   conditions   that   may   indicate
                attempts to spoof the mail system,  such  as
                using a non-standard queue directory.

      ProcessTitlePrefix=string
                [no  short  name]  Prefix  the process title
                shown on 'ps'  listings  with  string.   The
                string will be macro processed.

      QueueDirectory=dir
                [Q]  The  QueueDirectory  option  serves two
                purposes.  First, it specifies the directory
                or  set  of  directories  that  comprise the
                default queue group.  Second,  it  specifies
                the directory D which is the ancestor of all
                queue directories, and which  sendmail  uses
                as  its  current  working  directory.   When
                sendmail dumps  core,  it  leaves  its  core
                files  in  D.   There are two cases.  If dir
                ends     with     an      asterisk      (eg,
                /var/spool/mqueue/qd*),   then  all  of  the
                directories or symbolic links to directories
                beginning  with  `qd'  in  /var/spool/mqueue
                will be used as  queue  directories  of  the
                default  queue  group, and /var/spool/mqueue
                will be used as  the  working  directory  D.
                Otherwise,  dir  must name a directory (usu-
                ally /var/spool/mqueue): the  default  queue
                group consists of the single queue directory
                dir, and the working directory D is  set  to
____________________
   20N.B.:  the  noreceipts  flag  turns off support for RFC
1891 (Delivery Status Notification).











SMM:08-110         Sendmail Installation and Operation Guide


                dir.   To  define additional groups of queue
                directories, use the configuration file  `Q'
                command.   Do not change the queue directory
                structure while sendmail is running.

      QueueFactor=factor
                [q] Use factor as the multiplier in the  map
                function  to  decide  when  to just queue up
                jobs rather than run them.   This  value  is
                divided  by  the difference between the cur-
                rent load average and the load average limit
                (QueueLA  option)  to  determine the maximum
                message  priority   that   will   be   sent.
                Defaults to 600000.

      QueueLA=LA
                [x]  When the system load average exceeds LA
                and the QueueFactor (q)  option  divided  by
                the  difference  in the current load average
                and the QueueLA option plus one is less than
                the priority of the message, just queue mes-
                sages  (i.e.,  don't  try  to  send   them).
                Defaults  to  8  multiplied by the number of
                processors online on the system (if that can
                be determined).

      QueueFileMode=mode
                [no  short  name]  Default  permissions  for
                queue files (octal).  If not  set,  sendmail
                uses  0600 unless its real and effective uid
                are different in which case it uses 0644.

      QueueSortOrder=algorithm
                [no short name] Sets the algorithm used  for
                sorting the queue.  Only the first character
                of the value  is  used.   Legal  values  are
                "host"  (to  order  by the name of the first
                host name of the  first  recipient),  "file-
                name"  (to  order  by  the name of the queue
                file name), "time" (to order by the  submis-
                sion/creation time), "random" (to order ran-
                domly), "modification" (to order by the mod-
                ification time of the qf file (older entries
                first)), and "priority" (to order by message
                priority).   Host  ordering makes better use
                of the connection cache,  but  may  tend  to
                process  low  priority messages that go to a
                single host over high priority messages that
                go  to  several hosts; it probably shouldn't
                be used on slow network links.  Filename and
                modification  time  ordering saves the over-
                head of reading  all  of  the  queued  items
                before  starting  the  queue  run.  Creation










Sendmail Installation and Operation Guide         SMM:08-111


                (submission) time ordering is almost  always
                a bad idea, since it allows large, bulk mail
                to go out before smaller, personal mail, but
                may  have  applicability  on some hosts with
                very fast connections.  Random is useful  if
                several  queue  runners  are started by hand
                which try to drain the same queue since odds
                are  they will be working on different parts
                of the queue at  the  same  time.   Priority
                ordering is the default.

      QueueTimeout=timeout
                [T]  A  synonym  for  "Timeout.queuereturn".
                Use that form instead of the  "QueueTimeout"
                form.

      RandFile  [no short name] Name of file containing ran-
                dom data or the name of the UNIX  socket  if
                EGD  is used.  A (required) prefix "egd:" or
                "file:"  specifies   the   type.    STARTTLS
                requires  this  filename if the compile flag
                HASURANDOMDEV  is   not   set   (see   send-
                mail/README).

      ResolverOptions=options
                [I] Set resolver options.  Values can be set
                using +flag and  cleared  using  -flag;  the
                flags  can  be  "debug",  "aaonly", "usevc",
                "primary", "igntc",  "recurse",  "defnames",
                "stayopen",  "use_inet6",  or "dnsrch".  The
                string "HasWildcardMX" (without a  +  or  -)
                can   be  specified  to  turn  off  matching
                against MX records when doing name canonifi-
                cations.   The string "WorkAroundBrokenAAAA"
                (without a + or -) can be specified to  work
                around  some broken nameservers which return
                SERVFAIL (a  temporary  failure)  on  T_AAAA
                (IPv6)  lookups.  Notice: it might be neces-
                sary to apply the same (or similar)  options
                to submit.cf too.

      RrtImpliesDsn
                [R]  If  this  option  is  set,  a  "Return-
                Receipt-To:" header causes the request of  a
                DSN, which is sent to the envelope sender as
                required by RFC 1891,  not  to  the  address
                given in the header.

      RunAsUser=user
                [no  short name] The user parameter may be a
                user name (looked up in  /etc/passwd)  or  a
                numeric   user  id;  either  form  can  have
                ":group"  attached  (where  group   can   be










SMM:08-112         Sendmail Installation and Operation Guide


                numeric  or symbolic).  If set to a non-zero
                (non-root) value, sendmail  will  change  to
                this  user id shortly after startup21.  This
                avoids a certain class of security problems.
                However,  this means that all ".forward" and
                ":include:" files must be  readable  by  the
                indicated  user  and all files to be written
                must be writable by user Also, all file  and
                program  deliveries  will  be  marked unsafe
                unless the option DontBlameSendmail=NonRoot-
                SafeAddr  is set, in which case the delivery
                will be done as user.  It is also incompati-
                ble with the SafeFileEnvironment option.  In
                other words, it may not actually add much to
                security  on  an  average system, and may in
                fact detract from  security  (because  other
                file  permissions  must  be loosened).  How-
                ever, it should be useful on  firewalls  and
                other places where users don't have accounts
                and the aliases file is well constrained.

      RecipientFactor=fact
                [y] The indicated factor  is  added  to  the
                priority  (thus lowering the priority of the
                job) for each recipient,  i.e.,  this  value
                penalizes jobs with large numbers of recipi-
                ents.  Defaults to 30000.

      RefuseLA=LA
                [X] When the system load average exceeds LA,
                refuse  incoming SMTP connections.  Defaults
                to 12 multiplied by the number of processors
                online  on the system (if that can be deter-
                mined).

      RetryFactor=fact
                [Z] The factor  is  added  to  the  priority
                every  time  a job is processed.  Thus, each
                time a job is processed, its  priority  will
                be  decreased  by  the  indicated value.  In
                most environments this should  be  positive,
                since  hosts that are down are all too often
                down for a long time.  Defaults to 90000.

      SafeFileEnvironment=dir
                [no short name] If this option is set, send-
                mail will do a chroot(2) call into the indi-
                cated  directory  before  doing   any   file
____________________
   21When running as a daemon, it changes to this user after
accepting a connection but before reading any SMTP commands.












Sendmail Installation and Operation Guide         SMM:08-113


                writes.   If  the file name specified by the
                user begins with dir, that partial path name
                will be stripped off before writing, so (for
                example) if the SafeFileEnvironment variable
                is   set   to   "/safe"   then   aliases  of
                "/safe/logs/file" and "/logs/file"  actually
                indicate  the  same  file.  Additionally, if
                this option  is  set,  sendmail  refuses  to
                deliver to symbolic links.

      SaveFromLine
                [f]  Save  UNIX-style  "From"  lines  at the
                front of headers.  Normally they are assumed
                redundant and discarded.

      SharedMemoryKey
                [no short name] Key to use for shared memory
                segment; if not set (or  0),  shared  memory
                will  not  be  used.   Requires  support for
                shared memory to be compiled into  sendmail.
                If  this  option  is set, sendmail can share
                some data between different instances.   For
                example,  the  number  of entries in a queue
                directory or the available space in  a  file
                system.  This allows for more efficient pro-
                gram execution, since only one process needs
                to  update the data instead of each individ-
                ual process gathering the data each time  it
                is required.

      SendMimeErrors
                [j] If set, send error messages in MIME for-
                mat (see RFC 2045 and RFC 1344 for details).
                If  disabled,  sendmail  will not return the
                DSN keyword in response to an EHLO and  will
                not do Delivery Status Notification process-
                ing as described in RFC 1891.

      ServerCertFile
                [no short name] File containing the certifi-
                cate  of  the server, i.e., this certificate
                is used when sendmail acts as  server  (used
                for STARTTLS).

      ServerKeyFile
                [no  short name] File containing the private
                key  belonging  to  the  server  certificate
                (used for STARTTLS).

      ServiceSwitchFile=filename
                [no  short name] If your host operating sys-
                tem has a service switch abstraction  (e.g.,
                /etc/nsswitch.conf     on     Solaris     or










SMM:08-114         Sendmail Installation and Operation Guide


                /etc/svc.conf on Ultrix and DEC OSF/1)  that
                service will be consulted and this option is
                ignored.  Otherwise, this is the name  of  a
                file  that provides the list of methods used
                to implement particular services.  The  syn-
                tax is a series of lines, each of which is a
                sequence of words.  The first  word  is  the
                service  name,  and following words are ser-
                vice types.  The services that sendmail con-
                sults  directly  are  "aliases" and "hosts."
                Service types can  be  "dns",  "nis",  "nis-
                plus",  or "files" (with the caveat that the
                appropriate  support  must  be  compiled  in
                before  the  service can be referenced).  If
                ServiceSwitchFile  is  not   specified,   it
                defaults  to  /etc/mail/service.switch.   If
                that file does not exist, the default switch
                is:

                    aliases        files
                    hosts          dns nis files

                The    default   file   is   "/etc/mail/ser-
                vice.switch".

      SevenBitInput
                [7] Strip input to seven bits  for  compati-
                bility  with old systems.  This shouldn't be
                necessary.

      SingleLineFromHeader
                [no short name] If  set,  From:  lines  that
                have  embedded  newlines  are unwrapped onto
                one line.  This is to get around a botch  in
                Lotus  Notes  that  apparently cannot under-
                stand legally wrapped RFC 822 headers.

      SingleThreadDelivery
                [no short name] If  set,  a  client  machine
                will  never try to open two SMTP connections
                to a single server machine at the same time,
                even  in  different  processes.  That is, if
                another sendmail is already talking to  some
                host  a  new  sendmail will not open another
                connection.   This  property  is  of   mixed
                value; although this reduces the load on the
                other machine,  it  can  cause  mail  to  be
                delayed  (for  example,  if  one sendmail is
                delivering a huge message,  other  sendmails
                won't  be able to send even small messages).
                Also, it requires  another  file  descriptor
                (for  the  lock file) per connection, so you
                may have to reduce  the  ConnectionCacheSize










Sendmail Installation and Operation Guide         SMM:08-115


                option  to  avoid running out of per-process
                file descriptors.  Requires the  HostStatus-
                Directory option.

      SmtpGreetingMessage=message
                [$e macro] The message printed when the SMTP
                server starts up.  Defaults to "$j  Sendmail
                $v ready at $b".

      StatusFile=file
                [S]  Log  summary  statistics  in  the named
                file.   If  no  file  name   is   specified,
                "statistics"  is  used.  If not set, no sum-
                mary statistics are saved.  This  file  does
                not  grow  in size.  It can be printed using
                the mailstats(8) program.

      SuperSafe [s] This option can be set to  True,  False,
                or  Interactive.   If  set to True, sendmail
                will  be  super-safe  when  running  things,
                i.e.,  always  instantiate  the  queue file,
                even if you are going to  attempt  immediate
                delivery.   Sendmail always instantiates the
                queue file before returning control  to  the
                client under any circumstances.  This should
                really always be set to True.  The  Interac-
                tive  value  has been introduced in 8.12 and
                can be used  together  with  DeliveryMode=i.
                It  skips  some  synchronization calls which
                are effectively doubled in the  code  execu-
                tion path for this mode.

      TLSSrvOptions
                [no  short  name]  List  of options for SMTP
                STARTTLS for the server consisting of single
                characters  with  intervening white space or
                commas.  The flag ``V'' disables client ver-
                ification,  and  hence it is not possible to
                use a client certificate for relaying.  Cur-
                rently there are no other flags available.

      TempFileMode=mode
                [F]  The  file  mode  for  transcript files,
                files to which sendmail  delivers  directly,
                files  in  the HostStatusDirectory, and Sta-
                tusFile.  It  is  interpreted  in  octal  by
                default.  Defaults to 0600.

      Timeout.type=timeout
                [r; subsumes old T option as well] Set time-
                out values.  For more information, see  sec-
                tion 4.1.











SMM:08-116         Sendmail Installation and Operation Guide


      TimeZoneSpec=tzinfo
                [t]  Set  the local time zone info to tzinfo
                -- for  example,  "PST8PDT".   Actually,  if
                this is not set, the TZ environment variable
                is cleared (so the system default is  used);
                if  set  but null, the user's TZ variable is
                used, and if set and non-null the  TZ  vari-
                able is set to this value.

      TrustedUser=user
                [no  short name] The user parameter may be a
                user name (looked up in  /etc/passwd)  or  a
                numeric user id.  Trusted user for file own-
                ership and starting  the  daemon.   If  set,
                generated  alias  databases  and the control
                socket (if configured) will automatically be
                owned by this user.

      TryNullMXList
                [w]  If  this system is the "best" (that is,
                lowest preference) MX for a given host,  its
                configuration  rules  should normally detect
                this situation and treat that condition spe-
                cially  by  forwarding  the  mail  to a UUCP
                feed, treating it  as  local,  or  whatever.
                However,  in  some  cases  (such as Internet
                firewalls) you may want to  try  to  connect
                directly to that host as though it had no MX
                records at all.  Setting this option  causes
                sendmail  to try this.  The downside is that
                errors in your configuration are  likely  to
                be  diagnosed  as "host unknown" or "message
                timed out" instead of something  more  mean-
                ingful.  This option is disrecommended.

      UnixFromLine=fromline
                [$l  macro]  Defines  the  format  used when
                sendmail must add a  UNIX-style  From_  line
                (that      is,      a     line     beginning
                "From<space>user").  Defaults  to  "From  $g
                $d".   Don't  change this unless your system
                uses a different UNIX mailbox  format  (very
                unlikely).

      UnsafeGroupWrites
                [no  short name] If set (default), :include:
                and .forward files that are  group  writable
                are  considered "unsafe", that is, they can-
                not reference programs or write directly  to
                files.   World  writable :include: and .for-
                ward files are  always  unsafe.   Note:  use
                DontBlameSendmail  instead;  this  option is
                deprecated.










Sendmail Installation and Operation Guide         SMM:08-117


      UseErrorsTo
                [l] If there is an "Errors-To:" header, send
                error   messages  to  the  addresses  listed
                there.  They normally  go  to  the  envelope
                sender.   Use of this option causes sendmail
                to violate RFC 1123.  This option is disrec-
                ommended and deprecated.

      UserDatabaseSpec=udbspec
                [U] The user database specification.

      Verbose   [v]  Run  in  verbose mode.  If this is set,
                sendmail adjusts options HoldExpensive  (old
                c) and DeliveryMode (old d) so that all mail
                is delivered completely in a single  job  so
                that  you  can  see the entire delivery pro-
                cess.  Option Verbose should never be set in
                the  configuration  file; it is intended for
                command line use only.

      XscriptFileBufferSize=threshold
                [no short name] Set the threshold, in bytes,
                before  a memory-based queue transcript file
                becomes disk-based.   The  default  is  4096
                bytes.

      All options can be specified on the command line using
      the -O or -o flag, but most  will  cause  sendmail  to
      relinquish  its  set-user-ID permissions.  The options
      that will not cause this are SevenBitInput [7], Eight-
      BitMode  [8],  MinFreeBlocks  [b],  CheckpointInterval
      [C], DeliveryMode [d], ErrorMode [e], IgnoreDots  [i],
      SendMimeErrors [j], LogLevel [L], MeToo [m], OldStyle-
      Headers [o], PrivacyOptions [p], SuperSafe  [s],  Ver-
      bose [v], QueueSortOrder, MinQueueAge, DefaultCharSet,
      Dial    Delay,    NoRecipientAction,    ColonOkInAddr,
      MaxQueueRunSize,  SingleLineFromHeader,  and  AllowBo-
      gusHELO.  Actually, PrivacyOptions [p]  given  on  the
      command  line  are added to those already specified in
      the sendmail.cf  file,  i.e.,  they  can't  be  reset.
      Also, M (define macro) when defining the r or s macros
      is also considered "safe".

   5.7.  P -- Precedence Definitions

           Values for the "Precedence:" field may be defined
      using  the  P  control line.  The syntax of this field
      is:

          Pname=num

      When the name is found in a "Precedence:"  field,  the
      message  class  is  set  to  num.  Higher numbers mean










SMM:08-118         Sendmail Installation and Operation Guide


      higher precedence.  Numbers less than  zero  have  the
      special  property  that if an error occurs during pro-
      cessing the body of the message will not be  returned;
      this  is  expected  to be used for "bulk" mail such as
      through mailing  lists.   The  default  precedence  is
      zero.  For example, our list of precedences is:

          Pfirst-class=0
          Pspecial-delivery=100
          Plist=-30
          Pbulk=-60
          Pjunk=-100

      People  writing  mailing list exploders are encouraged
      to use "Precedence: list".  Older versions of sendmail
      (which discarded all error returns for negative prece-
      dences)  didn't  recognize  this  name,  giving  it  a
      default  precedence  of  zero.  This allows list main-
      tainers to see error returns on both old and new  ver-
      sions of sendmail.

   5.8.  V -- Configuration Version Level

           To  provide  compatibility with old configuration
      files, the V line has been added to define  some  very
      basic  semantics of the configuration file.  These are
      not intended to be long term  supports;  rather,  they
      describe compatibility features which will probably be
      removed in future releases.

           N.B.: these version levels  have  nothing  to  do
      with the version number on the files.  For example, as
      of this writing version 10 config files (specifically,
      8.10) used version level 9 configurations.

           "Old"  configuration files are defined as version
      level one.  Version level two files make the following
      changes:

       (1)   Host  name canonification ($[ ... $]) appends a
             dot if the name is recognized; this  gives  the
             config  file  a  way of finding out if anything
             matched.  (Actually, this just initializes  the
             "host"  map  with  the  "-a."   flag -- you can
             reset it to anything you  prefer  by  declaring
             the map explicitly.)

       (2)   Default   host  name  extension  is  consistent
             throughout processing; version level  one  con-
             figurations  turned  off domain extension (that
             is, adding the local domain name)  during  cer-
             tain  points  in processing.  Version level two
             configurations  are  expected  to   include   a










Sendmail Installation and Operation Guide         SMM:08-119


             trailing  dot  to  indicate  that  the  name is
             already canonical.

       (3)   Local names that are  not  aliases  are  passed
             through  a new distinguished ruleset five; this
             can be used to  append  a  local  relay.   This
             behavior  can  be  prevented  by  resolving the
             local name with an initial `@'.  That is, some-
             thing  that  resolves  to  a local mailer and a
             user name of "vikki"  will  be  passed  through
             ruleset  five, but a user name of "@vikki" will
             have the  `@'  stripped,  will  not  be  passed
             through  ruleset  five,  but  will otherwise be
             treated the same as  the  prior  example.   The
             expectation  is  that  this  might  be  used to
             implement a policy where mail sent  to  "vikki"
             was  handled by a central hub, but mail sent to
             "vikki@localhost" was delivered directly.

           Version level three files allow # initiated  com-
      ments  on all lines.  Exceptions are backslash escaped
      # marks and the $# syntax.

           Version level four configurations are  completely
      equivalent to level three for historical reasons.

           Version level five configuration files change the
      default definition of $w to be just the  first  compo-
      nent of the hostname.

           Version level six configuration files change many
      of the local processing options (such as aliasing  and
      matching  the beginning of the address for `|' charac-
      ters) to be mailer  flags;  this  allows  fine-grained
      control  over the special local processing.  Level six
      configuration files may also use  long  option  names.
      The  ColonOkInAddr  option  (to  allow  colons  in the
      local-part of addresses) defaults on  for  lower  num-
      bered  configuration  files;  the  configuration  file
      requires some additional intelligence to properly han-
      dle the RFC 822 group construct.

           Version  level seven configuration files used new
      option names to replace old macros  ($e  became  Smtp-
      GreetingMessage, $l became UnixFromLine, and $o became
      OperatorChars.  Also, prior to version seven, the  F=q
      flag  (use  250  instead  of 252 return value for SMTP
      VRFY commands) was assumed.

           Version level eight configuration files allow  $#
      on the left hand side of ruleset lines.












SMM:08-120         Sendmail Installation and Operation Guide


           Version  level  nine  configuration  files  allow
      parentheses in rulesets, i.e. they are not treated  as
      comments and hence removed.

           Version level ten configuration files allow queue
      group definitions.

           The V line may have an optional /vendor to  indi-
      cate  that  this configuration file uses modifications
      specific  to  a  particular  vendor22.   You  may  use
      "/Berkeley" to emphasize that this configuration  file
      uses the Berkeley dialect of sendmail.

   5.9.  K -- Key File Declaration

           Special maps can be defined using the line:

          Kmapname mapclass arguments

      The  mapname is the handle by which this map is refer-
      enced in the rewriting rules.   The  mapclass  is  the
      name  of a type of map; these are compiled in to send-
      mail.  The arguments are interpreted depending on  the
      class;  typically,  there  would  be a single argument
      naming the file containing the map.

           Maps are referenced using the syntax:

          $( map key $@ arguments $: default $)

      where either or both of the arguments or default  por-
      tion may be omitted.  The $@ arguments may appear more
      than once.  The indicated key and arguments are passed
      to  the appropriate mapping function.  If it returns a
      value, it replaces the input.  If it does not return a
      value  and  the  default  is  specified,  the  default
      replaces  the  input.    Otherwise,   the   input   is
      unchanged.

           The arguments are passed to the map for arbitrary
      use.  Most map classes can interpolate these arguments
      into  their values using the syntax "%n" (where n is a
      digit) to indicate the corresponding argument.   Argu-
      ment  "%0"  indicates  the database key.  For example,
      the rule

____________________
   22And of course, vendors are encouraged to add themselves
to  the  list  of  recognized vendors by editing the routine
setvendor in conf.c.  Please send e-mail  to  sendmail@Send-
mail.ORG to register your vendor dialect.












Sendmail Installation and Operation Guide         SMM:08-121


          R$- ! $+       $: $(uucp $1 $@ $2 $: $2 @ $1 . UUCP $)

      Looks up the UUCP name in a (user defined)  UUCP  map;
      if  not  found  it  turns  it  into ".UUCP" form.  The
      database might contain records like:

          decvax         %1@%0.DEC.COM
          research       %1@%0.ATT.COM

      Note that default clauses never do this mapping.

           The built-in map with both name and class  "host"
      is  the  host name canonicalization lookup.  Thus, the
      syntax:

          $(host hostname$)

      is equivalent to:

          $[hostname$]


           There are many defined classes.

      dbm       Database lookups using the ndbm(3)  library.
                Sendmail must be compiled with NDBM defined.

      btree     Database lookups using the  btree  interface
                to  the  Berkeley DB library.  Sendmail must
                be compiled with NEWDB defined.

      hash      Database lookups using the hash interface to
                the  Berkeley  DB library.  Sendmail must be
                compiled with NEWDB defined.

      nis       NIS lookups.  Sendmail must be compiled with
                NIS defined.

      nisplus   NIS+  lookups.   Sendmail  must  be compiled
                with NISPLUS defined.  The argument  is  the
                name  of  the  table to use for lookups, and
                the -k and -v flags may be used to  set  the
                key and value columns respectively.

      hesiod    Hesiod  lookups.   Sendmail must be compiled
                with HESIOD defined.

      ldap      LDAP X500 directory lookups.  Sendmail  must
                be  compiled  with LDAPMAP defined.  The map
                supports most of the standard arguments  and
                most  of  the  command line arguments of the
                ldapsearch program.  Note that, by  default,
                if  a  single query matches multiple values,










SMM:08-122         Sendmail Installation and Operation Guide


                only the first value will be returned unless
                the  -z  (value  separator) map flag is set.
                Also, the -1 map flag will treat a  multiple
                value return as if there were no matches.

      netinfo   NeXT NetInfo lookups.  Sendmail must be com-
                piled with NETINFO defined.

      text      Text file lookups.  The format of  the  text
                file  is  defined  by the -k (key field num-
                ber), -v (value field number), and -z (field
                delimiter) flags.

      ph        PH  query map.  Contributed and supported by
                Mark Roth, roth@uiuc.edu.  For more informa-
                tion,  consult  the  web  site  "http://www-
                dev.cso.uiuc.edu/sendmail/".

      nsd       nsd map for IRIX 6.5 and later.  Contributed
                and   supported   by   Bob   Mende  of  SGI,
                mende@sgi.com.

      stab      Internal symbol table lookups.  Used  inter-
                nally for aliasing.

      implicit  Really  should  be called "alias" -- this is
                used to get the default  lookups  for  alias
                files,  and  is  the  default if no class is
                specified for alias files.

      user      Looks up users using  getpwnam(3).   The  -v
                flag  can be used to specify the name of the
                field to return (although this  is  normally
                used only to check the existence of a user).

      host      Canonifies host domain names.  Given a  host
                name  it  calls  the name server to find the
                canonical name for that host.

      bestmx    Returns the best MX record for a  host  name
                given  as  the  key.  The current machine is
                always preferred -- that is, if the  current
                machine is one of the hosts listed as a low-
                est-preference MX record, then  it  will  be
                guaranteed to be returned.  This can be used
                to find out if this machine  is  the  target
                for  an  MX record, and mail can be accepted
                on that basis.  If the  -z  flag  is  given,
                then all MX names are returned, separated by
                the given delimiter.

      dns       This map requires the option -R  to  specify
                the  DNS resource record type to lookup. The










Sendmail Installation and Operation Guide         SMM:08-123


                following  types  are  supported:  A,  AAAA,
                AFSDB,  CNAME, MX, NS, PTR, SRV, and TXT.  A
                map lookup  will  return  only  one  record.
                Hence  for some types, e.g., MX records, the
                return value might be a  random  element  of
                the  list  due  to  randomizing  in  the DNS
                resolver.

      sequence  The arguments on the `K' line are a list  of
                maps;  the  resulting map searches the argu-
                ment maps in order until it  finds  a  match
                for  the indicated key.  For example, if the
                key definition is:

                    Kmap1 ...
                    Kmap2 ...
                    Kseqmap sequence map1 map2

                then a lookup against "seqmap" first does  a
                lookup  in  map1.   If  that  is  found,  it
                returns immediately.   Otherwise,  the  same
                key is used for map2.

      syslog    the  key  is  logged  via  syslogd(8).   The
                lookup returns the empty string.

      switch    Much like the "sequence" map except that the
                order  of  maps is determined by the service
                switch.  The argument is  the  name  of  the
                service to be looked up; the values from the
                service switch are appended to the map  name
                to  create new map names.  For example, con-
                sider the key definition:

                    Kali switch aliases

                together with the service switch entry:

                    aliases        nis files

                This causes a query against the map "ali" to
                search  maps named "ali.nis" and "ali.files"
                in that order.

      dequote   Strip double quotes (")  from  a  name.   It
                does  not  strip  backslashes,  and will not
                strip quotes if the resulting  string  would
                contain  unscannable  syntax (that is, basic
                errors like unbalanced angle brackets;  more
                sophisticated  errors  such as unknown hosts
                are not checked).  The  intent  is  for  use
                when trying to accept mail from systems such
                as DECnet that routinely  quote  odd  syntax










SMM:08-124         Sendmail Installation and Operation Guide


                such as

                    "49ers::ubell"

                A typical usage is probably something like:

                    Kdequote dequote

                    ...

                    R$-            $: $(dequote $1 $)
                    R$- $+         $: $>3 $1 $2

                Care  must  be  taken  to prevent unexpected
                results; for example,

                    "|someprogram < input > output"

                will have quotes stripped, but the result is
                probably  not  what you had in mind.  Fortu-
                nately these cases are rare.

      regex     The map definition on the K line contains  a
                regular  expression.   Any key input is com-
                pared to that  expression  using  the  POSIX
                regular   expressions   routines  regcomp(),
                regerr(), and regexec().  Refer to the docu-
                mentation for those routines for more infor-
                mation about the regular  expression  match-
                ing.  No rewriting of the key is done if the
                -m flag is used.  Without  it,  the  key  is
                discarded  or  if  -s if used, it is substi-
                tuted by the substring matches, delimited by
                $|  or  the string specified with the the -d
                flag.  The flags available for the map are

                    -n  not
                    -f  case sensitive
                    -b  basic regular expressions (default is extended)
                    -s  substring match
                    -d  set the delimiter used for -s
                    -a  append string to key
                    -m  match only, do not replace/discard value
                    -D  perform no lookup in deferred delivery mode.

                The -s flag can include an optional  parame-
                ter  which  can  be  used to select the sub-
                strings in the result of  the  lookup.   For
                example,

                    -s1,3,4

                Notes: to match a $ in a string, \$$ must be










Sendmail Installation and Operation Guide         SMM:08-125


                used.  If the pattern contains spaces,  they
                must be replaced with the blank substitution
                character, unless it is space itself.

      program   The arguments on the K line are the pathname
                to  a  program and any initial parameters to
                be passed.  When the map is called, the  key
                is  added  to the initial parameters and the
                program is invoked as the default user/group
                id.   The  first  line of standard output is
                returned as the value of the  lookup.   This
                has  many  potential  security problems, and
                has terrible performance; it should be  used
                only when absolutely necessary.

      macro     Set or clear a macro value.  To set a macro,
                pass the value as the first argument in  the
                map  lookup.   To clear a macro, do not pass
                an argument in  the  map  lookup.   The  map
                always returns the empty string.  Example of
                typical usage include:

                    Kstorage macro

                    ...

                    # set macro ${MyMacro} to the ruleset match
                    R$+ $: $(storage {MyMacro} $@ $1 $) $1
                    # set macro ${MyMacro} to an empty string
                    R$* $: $(storage {MyMacro} $@ $) $1
                    # clear macro ${MyMacro}
                    R$- $: $(storage {MyMacro} $) $1


      arith     Perform simple arithmetic  operations.   The
                operation  is  given as key, currently +, -,
                *, /, %, |, & (bitwise OR, AND), l (for less
                than),   and   =  are  supported.   The  two
                operands are given as arguments.  The lookup
                returns  the result of the computation, i.e.
                TRUE or FALSE for comparisons, integer  val-
                ues otherwise.  All options which are possi-
                ble for maps are ignored.  A simple  example
                is:

                    Kcomp arith

                    ...

                    Scheck_etrn
                    R$* $: $(comp l $@ $&{load_avg} $@ 7 $) $1
                    RFALSE$# error ...











SMM:08-126         Sendmail Installation and Operation Guide


           Most  of  these  accept  as  arguments  the  same
      optional flags and a filename (or a mapname  for  NIS;
      the filename is the root of the database path, so that
      ".db" or some  other  extension  appropriate  for  the
      database type will be added to get the actual database
      name).  Known flags are:

      -o        Indicates that this map is optional --  that
                is, if it cannot be opened, no error is pro-
                duced, and sendmail will behave  as  if  the
                map existed but was empty.

      -N, -O    If  neither -N or -O are specified, sendmail
                uses an adaptive algorithm to decide whether
                or  not to look for null bytes on the end of
                keys.  It starts by trying both; if it finds
                any  key  with  a  null  byte it never tries
                again without a null byte  and  vice  versa.
                If  -N is specified it never tries without a
                null byte and if -O is  specified  it  never
                tries  with  a  null  byte.   Setting one of
                these can speed matches but are never neces-
                sary.   If  both  -N  and  -O are specified,
                sendmail will never try any matches  at  all
                --  that is, everything will appear to fail.

      -ax       Append the string x on  successful  matches.
                For  example, the default host map appends a
                dot on successful matches.

      -Tx       Append the string x on  temporary  failures.
                For  example,  x  would be appended if a DNS
                lookup returned "server failed"  or  an  NIS
                lookup  could not locate a server.  See also
                the -t flag.

      -f        Do not fold upper to lower case before look-
                ing up the key.

      -m        Match  only  (without  replacing the value).
                If you only care about the  existence  of  a
                key  and  not  the  value (as you might when
                searching the  NIS  map  "hosts.byname"  for
                example),  this  flag  prevents the map from
                substituting the  value.   However,  The  -a
                argument  is  still appended on a match, and
                the default is  still  taken  if  the  match
                fails.

      -kkeycol  The  key  column  name  (for NIS+) or number
                (for text lookups).  For LDAP maps  this  is
                an   LDAP  filter  string  in  which  %s  is
                replaced with the literal  contents  of  the










Sendmail Installation and Operation Guide         SMM:08-127


                lookup  key and %0 is replaced with the LDAP
                escaped contents of the lookup key according
                to RFC 2254.

      -vvalcol  The  value  column name (for NIS+) or number
                (for text lookups).  For LDAP maps  this  is
                the  name  of  one  or more attributes to be
                returned; multiple attributes can  be  sepa-
                rated  by  commas.   If  not  specified, all
                attributes  found  in  the  match  will   be
                returned.

      -zdelim   The column delimiter (for text lookups).  It
                can be a single character or one of the spe-
                cial  strings  "\n" or "\t" to indicate new-
                line  or  tab  respectively.    If   omitted
                entirely,   the   column  separator  is  any
                sequence of white space.  For LDAP maps this
                is the separator character to combine multi-
                ple values into a single return string.   If
                not  set,  the  LDAP lookup will only return
                the first match found.

      -t        Normally, when a map attempts to do a lookup
                and   the   server   fails  (e.g.,  sendmail
                couldn't contact any name  server;  this  is
                not  the same as an entry not being found in
                the map), the  message  being  processed  is
                queued  for  future processing.  The -t flag
                turns off this behavior, letting the  tempo-
                rary  failure (server down) act as though it
                were a permanent failure (entry not  found).
                It  is  particularly useful for DNS lookups,
                where  someone  else's  misconfigured   name
                server  can  cause problems on your machine.
                However, care must be taken to  ensure  that
                you don't bounce mail that would be resolved
                correctly if  you  tried  again.   A  common
                strategy is to forward such mail to another,
                possibly better connected, mail server.

      -D        Perform no lookup in deferred delivery mode.
                This  flag  is  set  by default for the host
                map.

      -Sspacesub
                The character to use to replace space  char-
                acters  after  a successful map lookup (esp.
                useful for regex and syslog maps).

      -sspacesub
                For the dequote map only, the  character  to
                use  to  replace  space  characters  after a










SMM:08-128         Sendmail Installation and Operation Guide


                successful dequote.

      -q        Don't dequote the key before lookup.

      -Llevel   For the syslog map only,  it  specifies  the
                level to use for the syslog call.

      -A        When  rebuilding  an alias file, the -A flag
                causes duplicate entries in the text version
                to be merged.  For example, two entries:

                    list:user1, user2
                    list:user3

                would  be treated as though it were the sin-
                gle entry

                    list:user1, user2, user3

                in the presence of the -A flag.

           Some additional flags are available for the  host
      and dns maps:

      -d        delay: specify the resolver's retransmission
                time interval (in seconds).

      -r        retry:  specify  the  number  of  times   to
                retransmit a resolver query.

           The following additional flags are present in the
      ldap map only:

      -R        Do not auto chase referrals.  sendmail  must
                be  compiled  with  -DLDAP_REFERRALS  to use
                this flag.

      -n        Retrieve attribute names only.

      -Vsep     Retrieve both attributes name and  value(s),
                separated by sep.

      -rderef   Set  the  alias dereference option to one of
                never, always, search, or find.

      -sscope   Set search scope to one of  base,  one  (one
                level), or sub (subtree).

      -hhost    LDAP  server  hostname.  Some LDAP libraries
                allow you to specify  multiple,  space-sepa-
                rated  hosts  for  redundancy.  In addition,
                each of the hosts listed can be followed  by
                a  colon  and  a port number to override the










Sendmail Installation and Operation Guide         SMM:08-129


                default LDAP port.

      -bbase    LDAP search base.

      -pport    LDAP service port.

      -ltimelimit
                Time limit for LDAP queries.

      -Zsizelimit
                Size (number  of  matches)  limit  for  LDAP
                queries.

      -ddistinguished_name
                The  distinguished  name  to use to login to
                the LDAP server.

      -Mmethod  The  method  to  authenticate  to  the  LDAP
                server.   Should  be  one of LDAP_AUTH_NONE,
                LDAP_AUTH_SIMPLE, or LDAP_AUTH_KRBV4.

      -Ppasswordfile
                The file containing the secret key  for  the
                LDAP_AUTH_SIMPLE  authentication  method  or
                the name of the  Kerberos  ticket  file  for
                LDAP_AUTH_KRBV4.

      -1        Force  LDAP  searches  to  only succeed if a
                single match is found.  If  multiple  values
                are  found,  the  search is treated as if no
                match was found.

           The dbm map appends the strings ".pag" and ".dir"
      to  the given filename; the hash and btree maps append
      ".db".  For example, the map specification

          Kuucp dbm -o -N /etc/mail/uucpmap

      specifies an optional map named "uucp" of class "dbm";
      it  always  has null bytes at the end of every string,
      and      the      data       is       located       in
      /etc/mail/uucpmap.{dir,pag}.

           The  program  makemap(8) can be used to build any
      of the three database-oriented  maps.   It  takes  the
      following flags:

      -f        Do  not fold upper to lower case in the map.

      -N        Include null bytes in keys.

      -o        Append to an existing (old) file.











SMM:08-130         Sendmail Installation and Operation Guide


      -r        Allow replacement  of  existing  keys;  nor-
                mally,  re-inserting  an  existing key is an
                error.

      -v        Print what is happening.

      The sendmail daemon does not have to be  restarted  to
      read the new maps as long as you change them in place;
      file locking is used so that the maps  won't  be  read
      while they are being updated.

           New classes can be added in the routine setupmaps
      in file conf.c.

   5.10.  Q -- Queue Group Declaration

           In addition to the option  QueueDirectory,  queue
      groups  can be declared that define a (group of) queue
      directories under a common name.   The  syntax  is  as
      follows:

          Qname {, field=value}+

      where  name  is  the  symbolic name of the queue group
      under which it can be referenced in various places and
      the  "field=name" pairs define attributes of the queue
      group.  Fields are:

      Flags     Flags for this queue group.

      Nice      The nice(2) increment for the  queue  group.
                This value must be greater or equal zero.

      Interval  The time between two queue runs.

      Path      The queue directory of the group (required).

      Runners   The number of  parallel  runners  processing
                the queue.

      Jobs      The  maximum number of jobs (messages deliv-
                ered) per queue run.

      recipients
                The maximum number of recipients  per  enve-
                lope.   Envelopes with more than this number
                of recipients will be  split  into  multiple
                envelopes  in the same queue directory.  The
                default value 0 means no limit.

      Only the first character of the field name is checked.












Sendmail Installation and Operation Guide         SMM:08-131


           By default, a queue group named mqueue is defined
      that uses the value of the  QueueDirectory  option  as
      path.   Notice:  all  paths  that  are  used for queue
      groups  must  be  subdirectories  of   QueueDirectory.
      Since  they  can  be symbolic links, this isn't a real
      restriction, If QueueDirectory uses a  wildcard,  then
      the  directory one level up is considered the ``base''
      directory  which  all  other  queue  directories  must
      share.  Please make sure that the queue directories do
      not overlap, e.g., do not specify

          O QueueDirectory=/var/spool/mqueue/*
          Qone, P=/var/spool/mqueue/dir1
          Qtwo, P=/var/spool/mqueue/dir2

      because this also includes "dir1" and  "dir2"  in  the
      default queue group.  However,

          O QueueDirectory=/var/spool/mqueue/main*
          Qone, P=/var/spool/mqueue/dir
          Qtwo, P=/var/spool/mqueue/other*

      is a valid queue group specification.

           Options listed in the ``Flags'' field can be used
      to modify the behavior of a queue  group.   The  ``f''
      flag  must  be  set if multiple queue runners are sup-
      posed to work on the entries in a queue group.  Other-
      wise  sendmail  will  work  on  the  entries  strictly
      sequentially.

           The ``Interval''  field  sets  the  time  between
      queue  runs.   If  no queue group specific interval is
      set, then the parameter of the -q option from the com-
      mand line is used.

           To  control  the  overall  number of concurrently
      active queue runners the option  MaxQueueChildren  can
      be  set.  This limits the number of processes used for
      running the queues to MaxQueueChildren, though at  any
      one  time fewer processes may be active as a result of
      queue options, completed queue runs, system load, etc.

           The  maximum number of queue runners for an indi-
      vidual queue group can be controlled via  the  Runners
      option.  If set to 0, entries in the queue will not be
      processed, which is  useful  to  ``quarantine''  queue
      files.  The number of runners per queue group may also
      be  set  with  the  option  MaxRunnersPerQueue,  which
      applies to queue groups that have no individual limit.
      That is, the default  value  for  Runners  is  MaxRun-
      nersPerQueue if set, otherwise 1.











SMM:08-132         Sendmail Installation and Operation Guide


           The  field  Jobs  describes the maximum number of
      jobs (messages delivered) per queue run, which is  the
      queue group specific value of MaxQueueRunSize.

           Notice: queue groups should be declared after all
      queue related options  have  been  set  because  queue
      groups  take their defaults from those options.  If an
      option is set after a  queue  group  declaration,  the
      values  of  options  in the queue group are set to the
      defaults of sendmail unless explicitly set in the dec-
      laration.

           Each  envelope is assigned to a queue group based
      on the algorithm described in section  ``Queue  Groups
      and Queue Directories''.

   5.11.  X -- Mail Filter (Milter) Definitions

           The sendmail Mail Filter API (Milter) is designed
      to allow third-party programs access to mail  messages
      as  they  are being processed in order to filter meta-
      information and content.  They  are  declared  in  the
      configuration file as:

          Xname {, field=value}*

      where  name is the name of the filter (used internally
      only) and the "field=name" pairs define attributes  of
      the filter.  Also see the documentation for the Input-
      MailFilters option for more information.

           Fields are:

          Socket    The socket specification
          Flags     Special flags for this filter
          Timeouts  Timeouts for this filter

      Only the first character of the field name is  checked
      (it's case-sensitive).

           The  socket specification is one of the following
      forms:

          S=inet: port @ host


          S=inet6: port @ host


          S=local: path

      The first two describe an IPv4 or IPv6 socket  listen-
      ing  on  a certain port at a given host or IP address.










Sendmail Installation and Operation Guide         SMM:08-133


      The  final  form  describes  a  named  socket  on  the
      filesystem at the given path.

           The  following  flags  may  be  set in the filter
      description.

      R   Reject connection if filter unavailable.

      T   Temporary fail connection if filter unavailable.

           The timeouts can be set  using  the  four  fields
      inside of the T= equate:

      C   Timeout  for connecting to a filter.  If set to 0,
          the system's connect() timeout will be used.

      S   Timeout for sending information from the MTA to  a
          filter.

      R   Timeout for reading reply from the filter.

      E   Overall  timeout between sending end-of-message to
          filter and waiting for the final acknowledgment.

           Note the separator between each timeout field  is
      a   ';'.    The  default  values  (if  not  set)  are:
      T=C:5m;S:10s;R:10s;E:5m where s is seconds  and  m  is
      minutes.

           Examples:

          Xfilter1, S=local:/var/run/f1.sock, F=R
          Xfilter2, S=inet6:999@localhost, F=T, T=S:1s;R:1s;E:5m
          Xfilter3, S=inet:3333@localhost, T=C:2m


   5.12.  The User Database

           The  user  database  is  deprecated  in  favor of
      ``virtusertable'' and ``genericstable''  as  explained
      in the file cf/README.  If you have a version of send-
      mail with the user database package compiled  in,  the
      handling  of  sender  and recipient addresses is modi-
      fied.

           The location of this database is controlled  with
      the UserDatabaseSpec option.

      5.12.1.  Structure of the user database

              The  database is a sorted (BTree-based) struc-
         ture.  User records are stored with the key:











SMM:08-134         Sendmail Installation and Operation Guide


             user-name:field-name

         The  sorted  database  format  ensures  that   user
         records  are  clustered together.  Meta-information
         is always stored with a leading colon.

              Field names define both the syntax and  seman-
         tics of the value.  Defined fields include:

         maildrop  The   delivery  address  for  this  user.
                   There may  be  multiple  values  of  this
                   record.   In  particular,  mailing  lists
                   will have one maildrop  record  for  each
                   user on the list.

         mailname  The outgoing mailname for this user.  For
                   each outgoing name, there  should  be  an
                   appropriate maildrop record for that name
                   to   allow   return   mail.    See   also
                   :default:mailname.

         mailsender
                   Changes  any mail sent to this address to
                   have the indicated envelope sender.  This
                   is  intended  for mailing lists, and will
                   normally be the name  of  an  appropriate
                   -request  address.  It is very similar to
                   the owner-list syntax in the alias  file.

         fullname  The full name of the user.

         office-address
                   The office address for this user.

         office-phone
                   The office phone number for this user.

         office-fax
                   The office FAX number for this user.

         home-address
                   The home address for this user.

         home-phone
                   The home phone number for this user.

         home-fax  The home FAX number for this user.

         project   A (short) description of the project this
                   person is affiliated with.  In  the  Uni-
                   versity  this  is  often just the name of
                   their graduate advisor.











Sendmail Installation and Operation Guide         SMM:08-135


         plan      A pointer  to  a  file  from  which  plan
                   information can be gathered.

              As of this writing, only a few of these fields
         are actually being used by sendmail:  maildrop  and
         mailname.   A  finger  program  that uses the other
         fields is planned.

      5.12.2.  User database semantics

              When the rewriting rules submit an address  to
         the  local  mailer, the user name is passed through
         the alias file.  If no alias is found  (or  if  the
         alias  points  back  to the same address), the name
         (with ":maildrop" appended) is then used as  a  key
         in  the  user  database.  If no match occurs (or if
         the maildrop points at the same address),  forward-
         ing is tried.

              If  the  first token of the user name returned
         by ruleset 0 is an  "@"  sign,  the  user  database
         lookup  is  skipped.   The  intent is that the user
         database will act as a set of defaults for a  clus-
         ter  (in  our case, the Computer Science Division);
         mail sent to a specific machine should ignore these
         defaults.

              When  mail  is  sent,  the name of the sending
         user is looked up in the database.   If  that  user
         has  a  "mailname" record, the value of that record
         is used as their outgoing  name.   For  example,  I
         might have a record:

             eric:mailnameEric.Allman@CS.Berkeley.EDU

         This  would  cause  my  outgoing mail to be sent as
         Eric.Allman.

              If a "maildrop" is found for the user, but  no
         corresponding  "mailname" record exists, the record
         ":default:mailname" is consulted.  If present, this
         is  the  name of a host to override the local host.
         For example,  in  our  case  we  would  set  it  to
         "CS.Berkeley.EDU".  The effect is that anyone known
         in the database gets their outgoing mail stamped as
         "user@CS.Berkeley.EDU",  but  people  not listed in
         the database use the local hostname.
















SMM:08-136         Sendmail Installation and Operation Guide


      5.12.3.  Creating the database23

              The  user  database  is built from a text file
         using the makemap utility (in the  distribution  in
         the  makemap  subdirectory).   The  text  file is a
         series of lines corresponding  to  userdb  records;
         each  line has a key and a value separated by white
         space.  The key is always in the  format  described
         above -- for example:

             eric:maildrop

         This  file is normally installed in a system direc-
         tory;   for   example,   it   might    be    called
         /etc/mail/userdb.   To make the database version of
         the map, run the program:

             makemap btree /etc/mail/userdb < /etc/mail/userdb

         Then create a config  file  that  uses  this.   For
         example, using the V8 M4 configuration, include the
         following line in your .mc file:

             define(`confUSERDB_SPEC', /etc/mail/userdb.db)


6.  OTHER CONFIGURATION

        There are some configuration  changes  that  can  be
   made  by  recompiling  sendmail.   This section describes
   what changes can be made and what has to be  modified  to
   make  them.   In  most  cases  this should be unnecessary
   unless you are porting sendmail to a new environment.

   6.1.  Parameters in devtools/OS/$oscf

           These parameters are  intended  to  describe  the
      compilation  environment,  not site policy, and should
      normally be defined in the operating system configura-
      tion file.  This section needs a complete rewrite.

      NDBM      If  set,  the new version of the DBM library
                that allows multiple databases will be used.
                If  neither  NDBM  nor NEWDB are set, a much
                less efficient method  of  alias  lookup  is
                used.

____________________
   23These instructions are known to be  incomplete.   Other
features  are available which provide similar functionality,
e.g., virtual hosting and mapping  local  addresses  into  a
generic form as explained in cf/README.











Sendmail Installation and Operation Guide         SMM:08-137


      NEWDB     If  set,  use  the new database package from
                Berkeley (from  4.4BSD).   This  package  is
                substantially  faster  than DBM or NDBM.  If
                NEWDB and NDBM are both set,  sendmail  will
                read  DBM  files,  but  will  create and use
                NEWDB files.

      NIS       Include support for NIS.   If  set  together
                with both NEWDB and NDBM, sendmail will cre-
                ate both DBM and NEWDB files if and only  if
                an  alias file includes the substring "/yp/"
                in the name.  This is intended for  compati-
                bility  with  Sun Microsystems' mkalias pro-
                gram used on YP masters.

      NISPLUS   Compile in support for NIS+.

      NETINFO   Compile in support for  NetInfo  (NeXT  sta-
                tions).

      LDAPMAP   Compile  in  support  for LDAP X500 queries.
                Requires libldap and liblber from the  Umich
                LDAP   3.2  or  3.3  release  or  equivalent
                libraries for other LDAP libraries  such  as
                OpenLDAP.

      HESIOD    Compile in support for Hesiod.

      MAP_NSD   Compile in support for IRIX NSD lookups.

      MAP_REGEX Compile  in  support  for regular expression
                matching.

      DNSMAP    Compile in support for DNS  map  lookups  in
                the sendmail.cf file.

      PH_MAP    Compile in support for ph lookups.

      SASL      Compile in support for SASL, a required com-
                ponent for SMTP Authentication support.

      STARTTLS  Compile in support for STARTTLS.

      EGD       Compile in support for the "Entropy  Gather-
                ing  Daemon"  to  provide better random data
                for TLS.

      TCPWRAPPERS
                Compile in support for TCP Wrappers.

      _PATH_SENDMAILCF
                The pathname of the sendmail.cf file.











SMM:08-138         Sendmail Installation and Operation Guide


      _PATH_SENDMAILPID
                The pathname of the sendmail.pid file.

      SM_CONF_SHM
                Compile in support for  shared  memory,  see
                section about "/var/spool/mqueue".

      MILTER    Compile  in  support for contacting external
                mail filters built with the Milter API.

           There are also several compilation flags to indi-
      cate the environment such as "_AIX3" and "_SCO_unix_".
      See the sendmail/README file for the latest  scoop  on
      these flags.

   6.2.  Parameters in sendmail/conf.h

           Parameters and compilation options are defined in
      conf.h.  Most of these need not normally  be  tweaked;
      common  parameters  are  all in sendmail.cf.  However,
      the sizes of  certain  primitive  vectors,  etc.,  are
      included  in  this  file.   The  numbers following the
      parameters are their default value.

           This document is not the best source of  informa-
      tion  for  compilation  flags  in  conf.h -- see send-
      mail/README or sendmail/conf.h itself.

      MAXLINE [2048]
                  The maximum line length of any input line.
                  If  message  lines exceed this length they
                  will still be  processed  correctly;  how-
                  ever,  header  lines,  configuration  file
                  lines, alias lines, etc., must fit  within
                  this limit.

      MAXNAME [256]
                  The  maximum length of any name, such as a
                  host or a user name.

      MAXPV [256] The maximum number of  parameters  to  any
                  mailer.  This limits the number of recipi-
                  ents that may be passed  in  one  transac-
                  tion.  It can be set to any arbitrary num-
                  ber above about 10,  since  sendmail  will
                  break  up  a delivery into smaller batches
                  as needed.  A  higher  number  may  reduce
                  load on your system, however.

      MAXQUEUEGROUPS [50]
                  The maximum number of queue groups.












Sendmail Installation and Operation Guide         SMM:08-139


      MAXATOM [1000]
                  The  maximum number of atoms (tokens) in a
                  single address.  For example, the  address
                  "eric@CS.Berkeley.EDU" is seven atoms.

      MAXMAILERS [25]
                  The  maximum number of mailers that may be
                  defined in the configuration  file.   This
                  value is defined in include/sendmail/send-
                  mail.h.

      MAXRWSETS [200]
                  The maximum number of rewriting sets  that
                  may  be  defined.  The first half of these
                  are  reserved  for  numeric  specification
                  (e.g.,  ``S92''), while the upper half are
                  reserved   for    auto-numbering    (e.g.,
                  ``Sfoo'').   Thus,  with a value of 200 an
                  attempt to use ``S99'' will  succeed,  but
                  ``S100'' will fail.

      MAXPRIORITIES [25]
                  The  maximum  number  of  values  for  the
                  "Precedence:" field that  may  be  defined
                  (using the P line in sendmail.cf).

      MAXUSERENVIRON [100]
                  The  maximum  number  of items in the user
                  environment that will be passed to  subor-
                  dinate mailers.

      MAXMXHOSTS [100]
                  The  maximum  number of MX records we will
                  accept for any single host.

      MAXMAPSTACK [12]
                  The maximum number of  maps  that  may  be
                  "stacked" in a sequence class map.

      MAXMIMEARGS [20]
                  The  maximum number of arguments in a MIME
                  Content-Type: header; additional arguments
                  will be ignored.

      MAXMIMENESTING [20]
                  The  maximum  depth to which MIME messages
                  may be nested (that is, nested Message  or
                  Multipart  documents;  this does not limit
                  the number of components in a single  Mul-
                  tipart document).

      MAXDAEMONS [10]
                  The  maximum  number  of  sockets sendmail










SMM:08-140         Sendmail Installation and Operation Guide


                  will open  for  accepting  connections  on
                  different ports.

      MAXMACNAMELEN [25]
                  The maximum length of a macro name.

      A  number  of  other compilation options exist.  These
      specify whether or not specific code  should  be  com-
      piled in.  Ones marked with * are 0/1 valued.

      NETINET*    If set, support for Internet protocol net-
                  working is compiled in.  Previous versions
                  of  sendmail  referred  to this as DAEMON;
                  this old usage is now incorrect.  Defaults
                  on;  turn  it  off in the Makefile if your
                  system doesn't support the Internet proto-
                  cols.

      NETINET6*   If  set,  support  for  IPv6 networking is
                  compiled  in.   It  must   be   separately
                  enabled  by  adding DaemonPortOptions set-
                  tings.

      NETISO*     If set, support for ISO protocol  network-
                  ing  is compiled in (it may be appropriate
                  to #define this in the Makefile instead of
                  conf.h).

      NETUNIX*    If set, support for UNIX domain sockets is
                  compiled in.  This  is  used  for  control
                  socket support.

      LOG         If  set, the syslog routine in use at some
                  sites is used.   This  makes  an  informa-
                  tional  log  record  for each message pro-
                  cessed, and makes a  higher  priority  log
                  record   for   internal   system   errors.
                  STRONGLY RECOMMENDED --  if  you  want  no
                  logging,  turn it off in the configuration
                  file.

      MATCHGECOS* Compile in the code to do  ``fuzzy  match-
                  ing''  on  the GECOS field in /etc/passwd.
                  This also  requires  that  the  MatchGECOS
                  option be turned on.

      NAMED_BIND* Compile in code to use the Berkeley Inter-
                  net Name Domain (BIND) server  to  resolve
                  TCP/IP host names.

      NOTUNIX     If  you  are using a non-UNIX mail format,
                  you can set this flag to turn off  special
                  processing of UNIX-style "From " lines.










Sendmail Installation and Operation Guide         SMM:08-141


      USERDB*     Include  the  experimental  Berkeley  user
                  information database package.  This adds a
                  new  level of local name expansion between
                  aliasing and forwarding.  It also uses the
                  NEWDB  package.  This may change in future
                  releases.

      The following options are normally turned on  in  per-
      operating-system clauses in conf.h.

      IDENTPROTO* Compile  in  the IDENT protocol as defined
                  in RFC 1413.  This  defaults  on  for  all
                  systems  except  Ultrix,  which apparently
                  has the interesting "feature" that when it
                  receives  a  "host unreachable" message it
                  closes all open connections to that  host.
                  Since  some  firewall  gateways  send this
                  error code when you access an unauthorized
                  port  (such as 113, used by IDENT), Ultrix
                  cannot receive email from such hosts.

      SYSTEM5     Set  all  of  the  compilation  parameters
                  appropriate for System V.

      HASFLOCK*   Use Berkeley-style flock instead of System
                  V lockf to do file locking.   Due  to  the
                  highly  unusual  semantics of locks across
                  forks in lockf, this should always be used
                  if at all possible.

      HASINITGROUPS
                  Set  this  if  your  system  has the init-
                  groups() call (if you have multiple  group
                  support).   This is the default if SYSTEM5
                  is not defined or if you are on HPUX.

      HASUNAME    Set this if you have the  uname(2)  system
                  call  (or  corresponding library routine).
                  Set by default if SYSTEM5 is set.

      HASGETDTABLESIZE
                  Set this if you have the  getdtablesize(2)
                  system call.

      HASWAITPID  Set  this  if  you  have the haswaitpid(2)
                  system call.

      FAST_PID_RECYCLE
                  Set this if your system can possibly reuse
                  the same pid in the same second of time.

      SFS_TYPE    The mechanism that can be used to get file
                  system capacity information.   The  values










SMM:08-142         Sendmail Installation and Operation Guide


                  can  be one of SFS_USTAT (use the ustat(2)
                  syscall), SFS_4ARGS (use the four argument
                  statfs(2)  syscall),  SFS_VFS (use the two
                  argument   statfs(2)   syscall   including
                  <sys/vfs.h>), SFS_MOUNT (use the two argu-
                  ment    statfs(2)    syscall     including
                  <sys/mount.h>),  SFS_STATFS  (use  the two
                  argument   statfs(2)   syscall   including
                  <sys/statfs.h>),  SFS_STATVFS (use the two
                  argument   statfs(2)   syscall   including
                  <sys/statvfs.h>),  or  SFS_NONE (no way to
                  get this information).

      LA_TYPE     The  load  average  type.    Details   are
                  described below.

      The  are  several  built-in ways of computing the load
      average.  Sendmail tries to auto-configure them  based
      on  imperfect guesses; you can select one using the cc
      option -DLA_TYPE=type, where type is:

      LA_INT      The kernel stores the load average in  the
                  kernel  as an array of long integers.  The
                  actual  values  are  scaled  by  a  factor
                  FSCALE (default 256).

      LA_SHORT    The  kernel stores the load average in the
                  kernel as an array of short integers.  The
                  actual  values  are  scaled  by  a  factor
                  FSCALE (default 256).

      LA_FLOAT    The kernel stores the load average in  the
                  kernel  as  an  array  of double precision
                  floats.

      LA_MACH     Use MACH-style load averages.

      LA_SUBR     Call the getloadavg  routine  to  get  the
                  load average as an array of doubles.

      LA_ZERO     Always  return  zero  as the load average.
                  This is the fallback case.

      If type LA_INT, LA_SHORT, or  LA_FLOAT  is  specified,
      you  may  also need to specify _PATH_UNIX (the path to
      your system binary) and LA_AVENRUN (the  name  of  the
      variable  containing  the  load average in the kernel;
      usually "_avenrun" or "avenrun").

   6.3.  Configuration in sendmail/conf.c

           The following changes can be made in conf.c.











Sendmail Installation and Operation Guide         SMM:08-143


      6.3.1.  Built-in Header Semantics

              Not all header semantics are  defined  in  the
         configuration  file.  Header lines that should only
         be included by certain mailers (as  well  as  other
         more  obscure  semantics)  must be specified in the
         HdrInfo table in conf.c.  This table  contains  the
         header name (which should be in all lower case) and
         a set of header control  flags  (described  below),
         The flags are:

         H_ACHECK    Normally  when the check is made to see
                     if a header line is compatible  with  a
                     mailer,  sendmail  will  not  delete an
                     existing line.  If this  flag  is  set,
                     sendmail   will  delete  even  existing
                     header lines.  That is, if this bit  is
                     set  and  the mailer does not have flag
                     bits  set  that  intersect   with   the
                     required  mailer  flags  in  the header
                     definition in sendmail.cf,  the  header
                     line is always deleted.

         H_EOH       If  this  header field is set, treat it
                     like a blank line, i.e., it will signal
                     the end of the header and the beginning
                     of the message text.

         H_FORCE     Add  this  header  entry  even  if  one
                     existed  in  the  message before.  If a
                     header entry does  not  have  this  bit
                     set,  sendmail  will  not  add  another
                     header line if a header  line  of  this
                     name  already existed.  This would nor-
                     mally be used to stamp the  message  by
                     everyone who handled it.

         H_TRACE     If  set,  this  is  a timestamp (trace)
                     field.  If the number of  trace  fields
                     in  a  message  exceeds a preset amount
                     the message is returned on the  assump-
                     tion that it has an aliasing loop.

         H_RCPT      If  set,  this field contains recipient
                     addresses.  This is used by the -t flag
                     to  determine who to send to when it is
                     collecting recipients from the message.

         H_FROM      This  flag  indicates  that  this field
                     specifies a sender.  The order of these
                     fields  in  the HdrInfo table specifies
                     sendmail's preference for  which  field
                     to return error messages to.










SMM:08-144         Sendmail Installation and Operation Guide


         H_ERRORSTO  Addresses in this header should receive
                     error messages.

         H_CTE       This  header  is  a   Content-Transfer-
                     Encoding header.

         H_CTYPE     This header is a Content-Type header.

         H_STRIPVAL  Strip  the  value  from the header (for
                     Bcc:).

         Let's look at a sample HdrInfo specification:

             struct hdrinfo                    HdrInfo[] =
             {
                      /* originator fields, most to least significant  */
                 "resent-sender",              H_FROM,
                 "resent-from",                H_FROM,
                 "sender",                     H_FROM,
                 "from",                       H_FROM,
                 "full-name",                  H_ACHECK,
                 "errors-to",                  H_FROM|H_ERRORSTO,
                      /* destination fields */
                 "to",                         H_RCPT,
                 "resent-to",                  H_RCPT,
                 "cc",                         H_RCPT,
                 "bcc",                        H_RCPT|H_STRIPVAL,
                      /* message identification and control */
                 "message",                    H_EOH,
                 "text",                       H_EOH,
                      /* trace fields */
                 "received",                   H_TRACE|H_FORCE,
                      /* miscellaneous fields */
                 "content-transfer-encoding",  H_CTE,
                 "content-type",               H_CTYPE,

                 NULL,                         0,
             };

         This structure indicates that the  "To:",  "Resent-
         To:",   and  "Cc:"  fields  all  specify  recipient
         addresses.  Any "Full-Name:" field will be  deleted
         unless  the  required mailer flag (indicated in the
         configuration file) is specified.   The  "Message:"
         and "Text:" fields will terminate the header; these
         are used by random dissenters  around  the  network
         world.  The "Received:" field will always be added,
         and can be used to trace messages.

              There are a number of important  points  here.
         First,  header  fields  are not added automatically
         just because they are  in  the  HdrInfo  structure;
         they must be specified in the configuration file in










Sendmail Installation and Operation Guide         SMM:08-145


         order to be  added  to  the  message.   Any  header
         fields  mentioned in the configuration file but not
         mentioned in the  HdrInfo  structure  have  default
         processing  performed;  that  is,  they  are  added
         unless they were in the message  already.   Second,
         the  HdrInfo  structure only specifies cliched pro-
         cessing; certain headers are processed specially by
         ad  hoc  code regardless of the status specified in
         HdrInfo.  For example, the  "Sender:"  and  "From:"
         fields are always scanned on ARPANET mail to deter-
         mine the sender24; this  is  used  to  perform  the
         "return  to  sender"  function.   The  "From:"  and
         "Full-Name:" fields are used to determine the  full
         name  of  the sender if possible; this is stored in
         the macro $x and used in a number of ways.

      6.3.2.  Restricting Use of Email

              If it is necessary to restrict mail through  a
         relay,  the  checkcompat  routine  can be modified.
         This routine is called for every recipient address.
         It  returns an exit status indicating the status of
         the message.  The status EX_OK accepts the address,
         EX_TEMPFAIL queues the message for a later try, and
         other values (commonly EX_UNAVAILABLE)  reject  the
         message.  It is up to checkcompat to print an error
         message (using usrerr) if the message is  rejected.
         For example, checkcompat could read:



















____________________
   24Actually, this is no longer true in SMTP; this informa-
tion is contained in the envelope.  The older ARPANET proto-
cols did not completely distinguish envelope from header.












SMM:08-146         Sendmail Installation and Operation Guide


             int
             checkcompat(to, e)
                 register ADDRESS *to;
                 register ENVELOPE *e;
             {
                 register STAB *s;

                 s = stab("private", ST_MAILER, ST_FIND);
                 if (s != NULL && e->e_from.q_mailer != LocalMailer &&
                     to->q_mailer == s->s_mailer)
                 {
                     usrerr("No private net mail allowed through this machine");
                     return (EX_UNAVAILABLE);
                 }
                 if (MsgSize > 50000 && bitnset(M_LOCALMAILER, to->q_mailer))
                 {
                     usrerr("Message too large for non-local delivery");
                     e->e_flags |= EF_NORETURN;
                     return (EX_UNAVAILABLE);
                 }
                 return (EX_OK);
             }

         This would reject messages greater than 50000 bytes
         unless they were local.  The EF_NORETURN  flag  can
         be  set in e->e_flags to suppress the return of the
         actual body of the message  in  the  error  return.
         The  actual use of this routine is highly dependent
         on the implementation, and use should be limited.

      6.3.3.  New Database Map Classes

              New key maps can be added by creating a  class
         initialization  function  and  a  lookup  function.
         These are then added to the routine setupmaps.

              The initialization function is called as

             xxx_map_init(MAP *map, char *args)

         The map is an internal data structure.  The args is
         a  pointer to the portion of the configuration file
         line following the map class name; flags and  file-
         names  can  be  extracted from this line.  The ini-
         tialization function must return true  if  it  suc-
         cessfully opened the map, false otherwise.

              The lookup function is called as

             xxx_map_lookup(MAP *map, char buf[], char **av, int *statp)

         The  map  defines  the map internally.  The buf has
         the input key.  This may be  (and  often  is)  used










Sendmail Installation and Operation Guide         SMM:08-147


         destructively.   The  av  is  a  list  of arguments
         passed in from the rewrite line.  The lookup  func-
         tion  should return a pointer to the new value.  If
         the map lookup fails, *statp should be  set  to  an
         exit  status  code; in particular, it should be set
         to EX_TEMPFAIL if recovery is to  be  attempted  by
         the higher level code.

      6.3.4.  Queueing Function

              The routine shouldqueue is called to decide if
         a message should be  queued  or  processed  immedi-
         ately.   Typically this compares the message prior-
         ity to the current load average.  The default defi-
         nition is:

             bool
             shouldqueue(pri, ctime)
                 long pri;
                 time_t ctime;
             {
                 if (CurrentLA < QueueLA)
                     return false;
                 return (pri > (QueueFactor / (CurrentLA - QueueLA + 1)));
             }

         If  the  current load average (global variable Cur-
         rentLA,  which  is  set  before  this  function  is
         called) is less than the low threshold load average
         (option x, variable QueueLA),  shouldqueue  returns
         false  immediately  (that is, it should not queue).
         If  the  current  load  average  exceeds  the  high
         threshold   load   average   (option   X,  variable
         RefuseLA), shouldqueue  returns  true  immediately.
         Otherwise,  it  computes  the function based on the
         message  priority,  the  queue  factor  (option  q,
         global  variable  QueueFactor), and the current and
         threshold load averages.

              An implementation wishing to take  the  actual
         age  of  the  message into account can also use the
         ctime parameter, which is the time that the message
         was first submitted to sendmail.  Note that the pri
         parameter is already  weighted  by  the  number  of
         times  the  message  has  been tried (although this
         tends to lower the priority  of  the  message  with
         time);  the  expectation is that the ctime would be
         used as an "escape clause" to ensure that  messages
         are eventually processed.














SMM:08-148         Sendmail Installation and Operation Guide


      6.3.5.  Refusing Incoming SMTP Connections

              The function refuseconnections returns true if
         incoming SMTP connections should be  refused.   The
         current  implementation is based exclusively on the
         current load average and the  refuse  load  average
         option (option X, global variable RefuseLA):

             bool
             refuseconnections()
             {
                 return (RefuseLA > 0 && CurrentLA >= RefuseLA);
             }

         A  more  clever  implementation  could look at more
         system resources.

      6.3.6.  Load Average Computation

              The routine getla  returns  the  current  load
         average  (as  a rounded integer).  The distribution
         includes several possible implementations.  If  you
         are  porting  to  a new environment you may need to
         add some new tweaks.25

   6.4.  Configuration in sendmail/daemon.c

           The  file  sendmail/daemon.c contains a number of
      routines that are dependent on  the  local  networking
      environment.   The  version  supplied assumes you have
      BSD style sockets.

           In previous releases,  we  recommended  that  you
      modify the routine maphostname if you wanted to gener-
      alize $[ ... $] lookups.  We now  recommend  that  you
      create a new keyed map instead.

   6.5.  STARTTLS

           In  this section we assume that sendmail has been
      compiled  with  support  for  STARTTLS.   To  properly
      understand the use of STARTTLS in sendmail, it is nec-
      essary to understand at least some basics about  X.509
      certificates and public key cryptography.  This infor-
      mation can be found in books about SSL/TLS or  on  WWW
      sites, e.g., "http://www.OpenSSL.org/".


____________________
   25If  you  do,  please  send  updates  to  sendmail@Send-
mail.ORG.












Sendmail Installation and Operation Guide         SMM:08-149


      6.5.1.  Certificates for STARTTLS

              When  acting  as  a  server, sendmail requires
         X.509 certificates to support STARTTLS: one as cer-
         tificate  for the server (ServerCertFile and corre-
         sponding private ServerKeyFile) at least  one  root
         CA  (CACERTFile),  i.e., a certificate that is used
         to sign other certificates, and a path to a  direc-
         tory  which  contains  other CAs (CACERTPath).  The
         file specified via CACERTFile can  contain  several
         certificates of CAs.  The DNs of these certificates
         are sent to the client during the TLS handshake (as
         part  of  the  CertificateRequest)  as  the list of
         acceptable CAs.  However, do not list too many root
         CAs  in  that file, otherwise the TLS handshake may
         fail; e.g.,

             error:14094417:SSL routines:SSL3_READ_BYTES:
             sslv3 alert illegal parameter:s3_pkt.c:964:SSL alert number 47

         You should probably put only the CA cert into  that
         file that signed your own cert(s), or at least only
         those you trust.   The  CACERTPath  directory  must
         contain  the hashes of each CA certificate as file-
         names (or as links to them).  Symbolic links can be
         generated  with  the  following  two (Bourne) shell
         commands:

             C=FileName_of_CA_Certificate
             ln -s $C `openssl x509 -noout -hash < $C`.0

         An X.509 certificate is also required for authenti-
         cation  in  client  mode (ClientCertFile and corre-
         sponding private ClientKeyFile), however,  sendmail
         will  always use STARTTLS when offered by a server.
         The client and server certificates can  be  identi-
         cal.   Certificates can be obtained from a certifi-
         cate authority or created with the help of OpenSSL.
         The  required  format  for certificates and private
         keys is PEM.  To allow  for  automatic  startup  of
         sendmail,  private  keys (ServerKeyFile, ClientKey-
         File) must be stored  unencrypted.   The  keys  are
         only  protected by the permissions of the file sys-
         tem.  Never make a private key available to a third
         party.

      6.5.2.  PRNG for STARTTLS

              STARTTLS  requires a strong pseudo random num-
         ber generator (PRNG) to operate properly.   Depend-
         ing  on the TLS library you use, it may be required
         to explicitly initialize the PRNG with random data.
         OpenSSL  makes  use of /dev/urandom(4) if available










SMM:08-150         Sendmail Installation and Operation Guide


         (this corresponds  to  the  compile  flag  HASURAN-
         DOMDEV).   On  systems  which  lack this support, a
         random file must be specified  in  the  sendmail.cf
         file  using  the  option  RandFile.  It is strongly
         advised to use the "Entropy Gathering  Daemon"  EGD
         from  Brian Warner on those systems to provide use-
         ful random data.  In this case,  sendmail  must  be
         compiled with the flag EGD, and the RandFile option
         must  point  to  the  EGD   socket.    If   neither
         /dev/urandom(4)  nor EGD are available, you have to
         make sure that useful random data is available  all
         the time in RandFile.  If the file hasn't been mod-
         ified in the last 10 minutes before it is  supposed
         to  be  used  by sendmail the content is considered
         obsolete.  One method for generating this file is:

             openssl rand -out /etc/mail/randfile -rand /path/to/file:...256

         See the OpenSSL documentation for more information.
         In  this case, the PRNG for TLS is only seeded with
         other random data if the  DontBlameSendmail  option
         InsufficientEntropy  is  set.   This is most likely
         not sufficient for certain actions,  e.g.,  genera-
         tion of (temporary) keys.

              Please  see the OpenSSL documentation or other
         sources for further information about certificates,
         their creation and their usage, the importance of a
         good PRNG, and other aspects of TLS.

7.  ACKNOWLEDGEMENTS

        I've worked on sendmail for  many  years,  and  many
   employers  have  been remarkably patient about letting me
   work on a large project that was not part of my  official
   job.   This  includes  time  on the INGRES Project at the
   University of California at Berkeley, at Britton Lee, and
   again on the Mammoth and Titan Projects at Berkeley.

        Much of the second wave of improvements resulting in
   version 8.1 should be credited to Bryan Costales  of  the
   International  Computer  Science Institute.  As he passed
   me drafts of his book on sendmail I was inspired to start
   working  on  things  again.   Bryan was also available to
   bounce ideas off of.

        Gregory Neil Shapiro of Worcester Polytechnic Insti-
   tute  has  become  instrumental in all phases of sendmail
   support and development, and was largely responsible  for
   getting versions 8.8 and 8.9 out the door.

        Many,  many  people  contributed  chunks of code and
   ideas to sendmail.  It has proven to be a  group  network










Sendmail Installation and Operation Guide         SMM:08-151


   effort.   Version  8  in  particular was a group project.
   The following people and organizations made notable  con-
   tributions:

       Claus Assmann
       John Beck, Hewlett-Packard & Sun Microsystems
       Keith Bostic, CSRG, University of California, Berkeley
       Andrew Cheng, Sun Microsystems
       Michael J. Corrigan, University of California, San Diego
       Bryan Costales, International Computer Science Institute & InfoBeat
       Par (Pell) Emanuelsson
       Craig Everhart, Transarc Corporation
       Per Hedeland, Ericsson
       Tom Ivar Helbekkmo, Norwegian School of Economics
       Kari Hurtta, Finnish Meteorological Institute
       Allan E. Johannesen, WPI
       Jonathan Kamens, OpenVision Technologies, Inc.
       Takahiro Kanbe, Fuji Xerox Information Systems Co., Ltd.
       Brian Kantor, University of California, San Diego
       John Kennedy, Cal State University, Chico
       Murray S. Kucherawy, HookUp Communication Corp.
       Bruce Lilly, Sony U.S.
       Karl London
       Motonori Nakamura, Ritsumeikan University & Kyoto University
       John Gardiner Myers, Carnegie Mellon University
       Neil Rickert, Northern Illinois University
       Gregory Neil Shapiro, WPI
       Eric Schnoebelen, Convex Computer Corp.
       Eric Wassenaar, National Institute for Nuclear and High Energy Physics, Amsterdam
       Randall Winchester, University of Maryland
       Christophe Wolfhugel, Pasteur Institute & Herve Schauer Consultants (Paris)
       Exactis.com, Inc.

   I apologize for anyone I have omitted, misspelled, misat-
   tributed, or otherwise missed.  At this point, I  suspect
   that at least a hundred people have contributed code, and
   many more have contributed ideas, comments,  and  encour-
   agement.  I've tried to list them in the RELEASE_NOTES in
   the distribution directory.  I appreciate their contribu-
   tion as well.

        Special thanks are reserved for Michael Corrigan and
   Christophe Wolfhugel, who besides being wonderful  guinea
   pigs  and contributors have also consented to be added to
   the ``sendmail@Sendmail.ORG'' list and, by answering  the
   bulk of the questions sent to that list, have freed me up
   to do other work.



















                          APPENDIX  A


                      COMMAND LINE FLAGS




     Arguments  must  be   presented   with   flags   before
addresses.  The flags are:

-Ax       Select  an  alternative  .cf  file which is either
          sendmail.cf for -Am  or  submit.cf  for  -Ac.   By
          default the .cf file is chosen based on the opera-
          tion mode.  For -bm (default), -bs, and -t  it  is
          submit.cf if it exists, for all others it is send-
          mail.cf.

-bx       Set operation mode to x.  Operation modes are:

              m   Deliver mail (default)
              s   Speak SMTP on input side
              a*  ``Arpanet'' mode (get envelope sender information from header)
              d   Run as a daemon in background
              D   Run as a daemon in foreground
              t   Run in test mode
              v   Just verify addresses, don't collect or deliver
              i   Initialize the alias database
              p   Print the mail queue
              P   Print overview over the mail queue (requires shared memory)
              h   Print the persistent host status database
              H   Purge expired entries from the persistent host status database


-Btype    Indicate body type.

-Cfile    Use a different configuration file.  Sendmail runs
          as  the invoking user (rather than root) when this
          flag is specified.

-dlevel   Set debugging level.

-f addr   The envelope sender address is set to addr.   This
          address  may  also  be used in the From: header if
          that header is missing during initial  submission.
          The envelope sender address is used as the recipi-
          ent for delivery status notifications and may also
          appear in a Return-Path: header.

____________________
   *Deprecated.




SMM:08-152         Sendmail Installation and Operation Guide







Sendmail Installation and Operation Guide         SMM:08-153


-F name   Sets the full name of this user to name.

-G        When  accepting  messages  via  the  command line,
          indicate that they are for relay (gateway) submis-
          sion.   sendmail  may complain about syntactically
          invalid messages, e.g.,  unqualified  host  names,
          rather  than  fixing  them  when this flag is set.
          sendmail will not do any canonicalization in  this
          mode.

-h cnt    Sets  the "hop count" to cnt.  This represents the
          number of times this message has been processed by
          sendmail  (to  the  extent that it is supported by
          the underlying networks).  Cnt is incremented dur-
          ing  processing,  and  if  it reaches MAXHOP (cur-
          rently 25) sendmail throws away the  message  with
          an error.

-L tag    Sets  the  identifier  used for syslog.  Note that
          this identifier is set as early as possible.  How-
          ever,  sendmail  may  be  used  if  problems arise
          before the command line arguments are processed.

-n        Don't do aliasing or forwarding.

-N notifications
          Tag all addresses being sent as wanting the  indi-
          cated  notifications,  which  consists of the word
          "NEVER" or a comma-separated  list  of  "SUCCESS",
          "FAILURE",  and  "DELAY"  for successful delivery,
          failure, and a message that is stuck  in  a  queue
          somewhere.  The default is "FAILURE,DELAY".

-r addr   An obsolete form of -f.

-oxvalue  Set  option  x  to  the  specified  value.   These
          options are described in Section 5.6.

-Ooption=value
          Set option to the specified value (for  long  form
          option  names).   These  options  are described in
          Section 5.6.

-Mxvalue  Set macro x to the specified value.

-pprotocol
          Set the sending protocol.  Programs are encouraged
          to  set  this.   The  protocol field can be in the
          form protocol:host to set both the sending  proto-
          col and sending host.  For example, "-pUUCP:uunet"
          sets the sending protocol to UUCP and the  sending
          host to uunet.  (Some existing programs use -oM to
          set the r and s  macros;  this  is  equivalent  to










SMM:08-154         Sendmail Installation and Operation Guide


          using -p.)

-qtime    Try to process the queued up mail.  If the time is
          given, a sendmail will start one or more processes
          to  run through the queue(s) at the specified time
          interval to deliver  queued  mail;  otherwise,  it
          only runs once.  Each of these processes acts on a
          workgroup.  These  processes  are  also  known  as
          workgroup  processes  or  WGP's  for  short.  Each
          workgroup is responsible for controlling the  pro-
          cessing  of  one  or  more queues; workgroups help
          manage the use of system  resources  by  sendmail.
          Each  workgroup may have one or more children con-
          currently processing queues depending on the  set-
          ting of MaxQueueChildren.

-qptime   Similar  to  -q  with a time argument, except that
          instead of periodically  starting  WGP's  sendmail
          starts  persistent  WGP's  that  alternate between
          processing queues and sleeping.  The sleep time is
          specified  by  the time argument; it defaults to 1
          second, except that a WGP always sleeps at least 5
          seconds if their queues were empty in the previous
          run.  Persistent processes are managed by a  queue
          control process (QCP).  The QCP is the parent pro-
          cess of the WGP's.  Typically the QCP will be  the
          sendmail  daemon (when started with -bd or -bD) or
          a special  process  (named  Queue  control)  (when
          started  without -bd or -bD).  If a persistent WGP
          ceases to be active for some  reason  another  WGP
          will  be started by the QCP for the same workgroup
          in most cases. When  a  persistent  WGP  has  core
          dumped,  the  debug  flag no_persistent_restart is
          set  or  the  specific  persistent  WGP  has  been
          restarted too many times already then the WGP will
          not be started again and a message will be  logged
          to  this  effect.   To  stop  (SIGTERM) or restart
          (SIGHUP) persistent WGP's the  appropriate  signal
          should  be sent to the QCP. The QCP will propagate
          the signal to all of the WGP's and if  appropriate
          restart the persistent WGP's.

-qGname   Run the jobs in the queue group name once.

-q[!]Xstring
          Run  the  queue  once,  limiting the jobs to those
          matching Xstring.  The key letter X can  be  I  to
          limit  based on queue identifier, R to limit based
          on recipient, or S to limit based  on  sender.   A
          particular  queued  job  is accepted if one of the
          corresponding  addresses  contains  the  indicated
          string.  The optional ! character negates the con-
          dition tested.  Multiple -qX flags are  permitted,










Sendmail Installation and Operation Guide         SMM:08-155


          with  items  with  the  same  key  letter  "or'ed"
          together, and items  with  different  key  letters
          "and'ed" together.

-R ret    What  information you want returned if the message
          bounces; ret can be "HDRS"  for  headers  only  or
          "FULL"  for  headers plus body.  This is a request
          only; the other end is not required to  honor  the
          parameter.   If  "HDRS" is specified local bounces
          also return only the headers.

-t        Read the  header  for  "To:",  "Cc:",  and  "Bcc:"
          lines, and send to everyone listed in those lists.
          The "Bcc:" line will be  deleted  before  sending.
          Any  addresses  in  the  argument  vector  will be
          deleted from the send list.

-V envid  The indicated envid is passed with the envelope of
          the message and returned if the message bounces.

-X logfile
          Log  all  traffic  in  and  out of sendmail in the
          indicated logfile for debugging  mailer  problems.
          This  produces  a  lot  of  data  very quickly and
          should be used sparingly.

     There are a number of options that may be specified  as
primitive  flags.   These  are  the  e, i, m, and v options.
Also, the f option may be specified as the -s flag.  The DSN
related  options  "-N",  "-R",  and  "-V" have no effects on
sendmail running as daemon.



































                        APPENDIX  B


                     QUEUE FILE FORMATS




     This appendix describes the format of the queue  files.
These  files  live in a queue directory.  The individual qf,
df, and xf files may be stored in separate qf/, df/, and xf/
subdirectories if they are present in the queue directory.

     All  queue  files  have  the name ttYMDhmsNNppppp where
YMDhmsNNppppp is the id for this message and  the  tt  is  a
type.  The individual letters in the id are:

Y    Encoded year

M    Encoded month

D    Encoded day

h    Encoded hour

m    Encoded minute

s    Encoded second

NN   Encoded envelope number

ppppp
     At least five decimal digits of the process ID

     All files with the same id collectively define one mes-
sage.  Due to the use  of  memory-buffered  files,  some  of
these files may never appear on disk.

     The types are:

qf   The  queue control file.  This file contains the infor-
     mation necessary to process the job.

df   The data file.  The message body (excluding the header)
     is  kept  in  this  file.  Sometimes the df file is not
     stored in the same directory as the qf  file;  in  this
     case, the qf file contains a `d' record which names the
     queue directory that contains the df file.

tf   A temporary file.  This is an image of the qf file when
     it is being rebuilt.  It should be renamed to a qf file
     very quickly.



SMM:08-156         Sendmail Installation and Operation Guide







Sendmail Installation and Operation Guide         SMM:08-157


xf   A transcript file, existing during the life of  a  ses-
     sion  showing  everything that happens during that ses-
     sion.  Sometimes the xf file must be generated before a
     queue  group  has  been  selected; in this case, the xf
     file will be stored in a directory of the default queue
     group.

Qf   A  ``lost''  queue control file.  sendmail renames a qf
     file to Qf if there is a severe (configuration) problem
     that  cannot  be  solved  without  human  intervention.
     Search the logfile for the queue file id to figure  out
     what happened.  After you resolved the problem, you can
     rename the Qf file to qf and send it again.

     The qf file is structured as a  series  of  lines  each
beginning with a code letter.  The lines are as follows:

V    The  version  number  of the queue file format, used to
     allow new sendmail binaries to read queue files created
     by  older versions.  Defaults to version zero.  Must be
     the first line of the file if present.   For  8.12  the
     version number is 6.

A    The  information  given  by  the AUTH= parameter of the
     "MAIL FROM:" command or  $f@$j  if  sendmail  has  been
     called directly.

H    A  header definition.  There may be any number of these
     lines.  The order  is  important:  they  represent  the
     order  in the final message.  These use the same syntax
     as header definitions in the configuration file.

C    The    controlling    address.     The    syntax     is
     "localuser:aliasname".   Recipient  addresses following
     this line will be flagged so that  deliveries  will  be
     run  as the localuser (a user name from the /etc/passwd
     file); aliasname is the name of the alias that expanded
     to this address (used for printing messages).

Q    The  ``original  recipient'',  specified  by the ORCPT=
     field in an ESMTP transaction.   Used  exclusively  for
     Delivery  Status Notifications.  It applies only to the
     following `R' line.

r    The ``final recipient'' used for Delivery Status  Noti-
     fications.   It applies only to the following `R' line.

R    A recipient address.  This will normally be  completely
     aliased, but is actually realiased when the job is pro-
     cessed.  There will be one  line  for  each  recipient.
     Version  1 qf files also include a leading colon-termi-
     nated list of flags, which can be `S' to return a  mes-
     sage  on  successful  final  delivery,  `F' to return a










SMM:08-158         Sendmail Installation and Operation Guide


     message on failure, `D' to return a message if the mes-
     sage  is  delayed, `B' to indicate that the body should
     be returned, `N' to suppress returning  the  body,  and
     `P'  to  declare this as a ``primary'' (command line or
     SMTP-session) address.

S    The sender address.  There may only  be  one  of  these
     lines.

T    The job creation time.  This is used to compute when to
     time out the job.

P    The current message priority.  This is  used  to  order
     the  queue.  Higher numbers mean lower priorities.  The
     priority changes as the message sits in the queue.  The
     initial  priority  depends on the message class and the
     size of the message.

M    A message.  This line is printed by the mailq  command,
     and  is generally used to store status information.  It
     can contain any text.

F    Flag bits, represented as one letter per flag.  Defined
     flag bits are r indicating that this is a response mes-
     sage and w indicating that a warning message  has  been
     sent  announcing that the mail has been delayed.  Other
     flag bits are: 8: the body contains  8bit  data,  b:  a
     Bcc:  header  should  be  removed,  d: the mail has RET
     parameters (see RFC 1894), n: the body of  the  message
     should  not  be  returned  in  case of an error, s: the
     envelope has been split.

N    The total number of delivery attempts.

K    The time (as seconds since January 1, 1970) of the last
     delivery attempt.

d    If  the df file is in a different directory than the qf
     file, then a `d'  record  is  present,  specifying  the
     directory in which the df file resides.

I    The  i-number  of  the  data  file; this can be used to
     recover your mail queue after a disastrous disk  crash.

$    A  macro  definition.  The values of certain macros are
     passed through to the queue run phase.

B    The body type.  The remainder of the  line  is  a  text
     string  defining the body type.  If this field is miss-
     ing, the body type is assumed to be "undefined" and  no
     special  processing  is  attempted.   Legal  values are
     "7BIT" and "8BITMIME".











Sendmail Installation and Operation Guide         SMM:08-159


Z    The original envelope id (from the ESMTP  transaction).
     For Deliver Status Notifications only.

     As  an  example,  the following is a queue file sent to
"eric@mammoth.Berkeley.EDU"  and   "bostic@okeeffe.CS.Berke-
ley.EDU"1:

    V4
    T711358135
    K904446490
    N0
    P2100941
    $_eric@localhost
    ${daemon_flags}
    Seric
    Ceric:100:1000:sendmail@vangogh.CS.Berkeley.EDU
    RPFD:eric@mammoth.Berkeley.EDU
    RPFD:bostic@okeeffe.CS.Berkeley.EDU
    H?P?Return-path: <^g>
    H??Received: by vangogh.CS.Berkeley.EDU (5.108/2.7) id AAA06703;
        Fri, 17 Jul 1992 00:28:55 -0700
    H??Received: from mail.CS.Berkeley.EDU by vangogh.CS.Berkeley.EDU (5.108/2.7)
        id AAA06698; Fri, 17 Jul 1992 00:28:54 -0700
    H??Received: from [128.32.31.21] by mail.CS.Berkeley.EDU (5.96/2.5)
        id AA22777; Fri, 17 Jul 1992 03:29:14 -0400
    H??Received: by foo.bar.baz.de (5.57/Ultrix3.0-C)
        id AA22757; Fri, 17 Jul 1992 09:31:25 GMT
    H?F?From: eric@foo.bar.baz.de (Eric Allman)
    H?x?Full-name: Eric Allman
    H??Message-id: <9207170931.AA22757@foo.bar.baz.de>
    H??To: sendmail@vangogh.CS.Berkeley.EDU
    H??Subject: this is an example message

This  shows  the person who sent the message, the submission
time (in seconds since January 1, 1970), the message  prior-
ity,  the message class, the recipients, and the headers for
the message.










____________________
   1This  example  is  contrived and probably inaccurate for
your environment.  Glance over it to get  an  idea;  nothing
can replace looking at what your own system generates.















                        APPENDIX  C


                  SUMMARY OF SUPPORT FILES




     This is a summary of the support  files  that  sendmail
creates or generates.  Many of these can be changed by edit-
ing the sendmail.cf file; check there  to  find  the  actual
pathnames.

/usr/sbin/sendmail
          The binary of sendmail.

/usr/bin/newaliases
          A  link  to  /usr/sbin/sendmail;  causes the alias
          database to be rebuilt.  Running this  program  is
          completely  equivalent  to giving sendmail the -bi
          flag.

/usr/bin/mailq
          Prints a listing of the mail queue.  This  program
          is equivalent to using the -bp flag to sendmail.

/etc/mail/sendmail.cf
          The configuration file, in textual form.

/etc/mail/helpfile
          The SMTP help file.

/etc/mail/statistics
          A statistics file; need not be present.

/etc/mail/sendmail.pid
          Created in daemon mode; it contains the process id
          of the current SMTP daemon.  If you  use  this  in
          scripts;  use  ``head  -1''  to get just the first
          line; the second line contains  the  command  line
          used  to  invoke the daemon, and later versions of
          sendmail may add more  information  to  subsequent
          lines.

/etc/mail/aliases
          The textual version of the alias file.

/etc/mail/aliases.db
          The alias file in hash(3) format.

/etc/mail/aliases.{pag,dir}
          The alias file in ndbm(3) format.



SMM:08-160         Sendmail Installation and Operation Guide







Sendmail Installation and Operation Guide         SMM:08-161


/var/spool/mqueue
          The  directory in which the mail queue(s) and tem-
          porary files reside.

/var/spool/mqueue/qf*
          Control (queue) files for messages.

/var/spool/mqueue/df*
          Data files.

/var/spool/mqueue/tf*
          Temporary versions of the qf  files,  used  during
          queue file rebuild.

/var/spool/mqueue/xf*
          A transcript of the current session.















































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Sendmail Installation and Operation Guide           SMM:08-3


                          TABLE OF CONTENTS

1.  BASIC INSTALLATION ................................    7
   1.1.  Compiling Sendmail ...........................    7
      1.1.1.  Tweaking the Build Invocation ...........    7
      1.1.2.  Creating a Site Configuration File ......    8
      1.1.3.  Tweaking the Makefile ...................    8
      1.1.4.  Compilation and installation ............    9
   1.2.  Configuration Files ..........................   10
   1.3.  Details of Installation Files ................   12
      1.3.1.  /usr/sbin/sendmail ......................   12
      1.3.2.  /etc/mail/sendmail.cf ...................   12
      1.3.3.  /etc/mail/submit.cf .....................   13
      1.3.4.  /usr/bin/newaliases .....................   13
      1.3.5.  /usr/bin/hoststat .......................   13
      1.3.6.  /usr/bin/purgestat ......................   13
      1.3.7.  /var/spool/mqueue .......................   14
      1.3.8.  /var/spool/clientmqueue .................   14
      1.3.9.  /var/spool/mqueue/.hoststat .............   15
      1.3.10.  /etc/mail/aliases* .....................   15
      1.3.11.  /etc/rc or /etc/init.d/sendmail ........   15
      1.3.12.  /etc/mail/helpfile .....................   16
      1.3.13.  /etc/mail/statistics ...................   16
      1.3.14.  /usr/bin/mailq .........................   16
      1.3.15.  sendmail.pid ...........................   18
      1.3.16.  Map Files ..............................   18
2.  NORMAL OPERATIONS .................................   18
   2.1.  The System Log ...............................   18
      2.1.1.  Format ..................................   18
      2.1.2.  Levels ..................................   20
   2.2.  Dumping State ................................   20
   2.3.  The Mail Queues ..............................   20
      2.3.1.  Queue Groups and Queue Directories ......   21
      2.3.2.  Queue Runs ..............................   22
      2.3.3.  Manual Intervention .....................   22
      2.3.4.  Printing the queue ......................   22
      2.3.5.  Forcing the queue .......................   23
   2.4.  Disk Based Connection Information ............   24
   2.5.  The Service Switch ...........................   26
   2.6.  The Alias Database ...........................   26
      2.6.1.  Rebuilding the alias database ...........   28
      2.6.2.  Potential problems ......................   29
      2.6.3.  List owners .............................   29
   2.7.  User Information Database ....................   30
   2.8.  Per-User Forwarding (.forward Files) .........   30
   2.9.  Special Header Lines .........................   30
      2.9.1.  Errors-To: ..............................   31
      2.9.2.  Apparently-To: ..........................   31
      2.9.3.  Precedence ..............................   31
   2.10.  IDENT Protocol Support ......................   31
3.  ARGUMENTS .........................................   32
   3.1.  Queue Interval ...............................   33
   3.2.  Daemon Mode ..................................   33










SMM:08-4           Sendmail Installation and Operation Guide


   3.3.  Forcing the Queue ............................   33
   3.4.  Debugging ....................................   34
   3.5.  Changing the Values of Options ...............   35
   3.6.  Trying a Different Configuration File ........   35
   3.7.  Logging Traffic ..............................   36
   3.8.  Testing Configuration Files ..................   36
   3.9.  Persistent Host Status Information ...........   38
4.  TUNING ............................................   38
   4.1.  Timeouts .....................................   39
      4.1.1.  Queue interval ..........................   39
      4.1.2.  Read timeouts ...........................   39
      4.1.3.  Message timeouts ........................   42
   4.2.  Forking During Queue Runs ....................   43
   4.3.  Queue Priorities .............................   44
   4.4.  Load Limiting ................................   45
   4.5.  Resource Limits ..............................   45
   4.6.  Delivery Mode ................................   45
   4.7.  Log Level ....................................   46
   4.8.  File Modes ...................................   47
      4.8.1.  To suid or not to suid?  ................   47
      4.8.2.  Turning off security checks .............   48
   4.9.  Connection Caching ...........................   52
   4.10.  Name Server Access ..........................   52
   4.11.  Moving the Per-User Forward Files ...........   54
   4.12.  Free Space ..................................   55
   4.13.  Maximum Message Size ........................   55
   4.14.  Privacy Flags ...............................   55
   4.15.  Send to Me Too ..............................   56
5.  THE WHOLE SCOOP ON THE CONFIGURATION FILE .........   56
   5.1.  R and S -- Rewriting Rules ...................   56
      5.1.1.  The left hand side ......................   57
      5.1.2.  The right hand side .....................   58
      5.1.3.  Semantics of rewriting rule sets ........   60
      5.1.4.  Ruleset hooks ...........................   61
         5.1.4.1.  check_relay ........................   62
         5.1.4.2.  check_mail .........................   62
         5.1.4.3.  check_rcpt .........................   62
         5.1.4.4.  check_data .........................   62
         5.1.4.5.  check_compat .......................   62
         5.1.4.6.  check_eoh ..........................   62
         5.1.4.7.  check_etrn .........................   63
         5.1.4.8.  check_expn .........................   63
         5.1.4.9.  check_vrfy .........................   63
         5.1.4.10.  trust_auth ........................   64
         5.1.4.11.  tls_client ........................   64
         5.1.4.12.  tls_server ........................   64
         5.1.4.13.  tls_rcpt ..........................   64
         5.1.4.14.  srv_features ......................   65
         5.1.4.15.  try_tls ...........................   65
         5.1.4.16.  authinfo ..........................   65
         5.1.4.17.  queuegroup ........................   66
      5.1.5.  IPC mailers .............................   66
   5.2.  D -- Define Macro ............................   67










Sendmail Installation and Operation Guide           SMM:08-5


   5.3.  C and F -- Define Classes ....................   77
   5.4.  M -- Define Mailer ...........................   79
   5.5.  H -- Define Header ...........................   87
   5.6.  O -- Set Option ..............................   89
   5.7.  P -- Precedence Definitions ..................  117
   5.8.  V -- Configuration Version Level .............  118
   5.9.  K -- Key File Declaration ....................  120
   5.10.  Q -- Queue Group Declaration ................  130
   5.11.  X -- Mail Filter (Milter) Definitions .......  132
   5.12.  The User Database ...........................  133
      5.12.1.  Structure of the user database .........  133
      5.12.2.  User database semantics ................  135
      5.12.3.  Creating the database23 ................  135
6.  OTHER CONFIGURATION ...............................  136
   6.1.  Parameters in devtools/OS/$oscf ..............  136
   6.2.  Parameters in sendmail/conf.h ................  138
   6.3.  Configuration in sendmail/conf.c .............  142
      6.3.1.  Built-in Header Semantics ...............  143
      6.3.2.  Restricting Use of Email ................  145
      6.3.3.  New Database Map Classes ................  146
      6.3.4.  Queueing Function .......................  147
      6.3.5.  Refusing Incoming SMTP Connections ......  148
      6.3.6.  Load Average Computation ................  148
   6.4.  Configuration in sendmail/daemon.c ...........  148
   6.5.  STARTTLS .....................................  148
      6.5.1.  Certificates for STARTTLS ...............  149
      6.5.2.  PRNG for STARTTLS .......................  149
7.  ACKNOWLEDGEMENTS ..................................  150
Appendix A.  COMMAND LINE FLAGS .......................  152
Appendix B.  QUEUE FILE FORMATS .......................  156
Appendix C.  SUMMARY OF SUPPORT FILES .................  160
































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