    PIPE(8)                                                                PIPE(8)

    NAME
           pipe - Postfix delivery to external command

    SYNOPSIS
           pipe [generic Postfix daemon options] command_attributes...

    DESCRIPTION
           The  pipe(8)  daemon  processes  requests from the Postfix
           queue manager to deliver messages  to  external  commands.
           This  program expects to be run from the master(8) process
           manager.

           Message  attributes  such  as  sender  address,  recipient
           address  and  next-hop  host name can be specified as com-
           mand-line macros that are  expanded  before  the  external
           command is executed.

           The  pipe(8)  daemon updates queue files and marks recipi-
           ents as finished, or it informs  the  queue  manager  that
           delivery  should  be tried again at a later time. Delivery
           status reports are sent  to  the  bounce(8),  defer(8)  or
           trace(8) daemon as appropriate.

    SINGLE-RECIPIENT DELIVERY
           Some external commands cannot handle more than one recipi-
           ent per delivery request. Examples of such transports  are
           pagers or fax machines.

           To  prevent  Postfix  from sending multiple recipients per
           delivery request, specify

               transport_destination_recipient_limit = 1

           in the Postfix main.cf file, where transport is  the  name
           in the first column of the Postfix master.cf entry for the
           pipe-based delivery transport.

    COMMAND ATTRIBUTE SYNTAX
           The external command attributes are given in the master.cf
           file at the end of a service definition.  The syntax is as
           follows:

           chroot=pathname (optional)
                  Change  the  process  root  directory  and  working
                  directory  to  the  named  directory.  This happens
                  before switching to the privileges  specified  with
                  the   user  attribute,  and  before  executing  the
                  optional directory=pathname directive. Delivery  is
                  deferred in case of failure.

                  This feature is available as of Postfix 2.3.

           directory=pathname (optional)
                  Change  to the named directory before executing the
                  external command.  The directory must be accessible
                  for the user specified with the user attribute (see
                  below).    The   default   working   directory   is
                  $queue_directory.   Delivery is deferred in case of
                  failure.

                  This feature is available as of Postfix 2.2.

           eol=string (optional, default: \n)
                  The output record delimiter.  Typically  one  would
                  use  either \r\n or \n. The usual C-style backslash
                  escape sequences are recognized: \a \b \f \n \r  \t
                  \v \ddd (up to three octal digits) and \\.

           flags=BDFORhqu.> (optional)
                  Optional  message  processing  flags. By default, a
                  message is copied unchanged.

                  B      Append a blank line at the end of each  mes-
                         sage.  This  is  required  by some mail user
                         agents that recognize  "From  "  lines  only
                         when preceded by a blank line.

                  D      Prepend  a "Delivered-To: recipient" message
                         header with the envelope recipient  address.
                         Note: for this to work, the transport_desti-
                         nation_recipient_limit must be 1.

                         This feature is available as of Postfix 2.0.

                  F      Prepend  a "From sender time_stamp" envelope
                         header to  the  message  content.   This  is
                         expected by, for example, UUCP software.

                  O      Prepend  an  "X-Original-To: recipient" mes-
                         sage header with the  recipient  address  as
                         given  to  Postfix.  Note: for this to work,
                         the    transport_destination_recipient_limit
                         must be 1.

                         This feature is available as of Postfix 2.0.

                  R      Prepend a Return-Path: message  header  with
                         the envelope sender address.

                  h      Fold the command-line $recipient domain name
                         and $nexthop host name to lower case.   This
                         is recommended for delivery via UUCP.

                  q      Quote  white space and other special charac-
                         ters in the command-line $sender and $recip-
                         ient address localparts (text to the left of
                         the right-most @ character), according to an
                         8-bit  transparent version of RFC 822.  This
                         is recommended  for  delivery  via  UUCP  or
                         BSMTP.

                         The  result  is  compatible with the address
                         parsing of command-line  recipients  by  the
                         Postfix sendmail(1) mail submission command.

                         The q flag affects  only  entire  addresses,
                         not the partial address information from the
                         $user, $extension or  $mailbox  command-line
                         macros.

                  u      Fold  the  command-line  $recipient  address
                         localpart (text to the left  of  the  right-
                         most  @  character)  to lower case.  This is
                         recommended for delivery via UUCP.

                  .      Prepend "." to lines starting with ".". This
                         is needed by, for example, BSMTP software.

                  >      Prepend  ">" to lines starting with "From ".
                         This is expected by, for example, UUCP soft-
                         ware.

           null_sender=replacement (default: MAILER-DAEMON)
                  Replace the null sender address, which is typically
                  used for delivery status  notifications,  with  the
                  specified  text when expanding the $sender command-
                  line macro, and when generating a From_ or  Return-
                  Path: message header.

                  If  the null sender replacement text is a non-empty
                  string then it  is  affected  by  the  q  flag  for
                  address quoting in command-line arguments.

                  The null sender replacement text may be empty; this
                  form is recommended for content filters  that  feed
                  mail back into Postfix. The empty sender address is
                  not affected by the q flag for address  quoting  in
                  command-line arguments.

                  Caution: a null sender address is easily mis-parsed
                  by naive software. For example,  when  the  pipe(8)
                  daemon executes a command such as:

                      command -f$sender -- $recipient (bad)

                  the command will mis-parse the -f option value when
                  the sender address is a null string.   For  correct
                  parsing, specify $sender as an argument by itself:

                      command -f $sender -- $recipient (good)

                  This  feature  is  available  with  Postfix 2.3 and
                  later.

           size=size_limit (optional)
                  Messages greater in size than this limit (in bytes)
                  will be returned to the sender as undeliverable.

           user=username (required)

           user=username:groupname
                  Execute the external command with the rights of the
                  specified username.  The software refuses  to  exe-
                  cute  commands  with  root  privileges, or with the
                  privileges of the mail system owner.  If  groupname
                  is  specified,  the  corresponding group ID is used
                  instead of the group ID of username.

           argv=command... (required)
                  The command to be executed. This must be  specified
                  as the last command attribute.  The command is exe-
                  cuted  directly,  i.e.  without  interpretation  of
                  shell  meta  characters  by  a shell command inter-
                  preter.

                  In  the  command  argument  vector,  the  following
                  macros are recognized and replaced with correspond-
                  ing information  from  the  Postfix  queue  manager
                  delivery request.

                  In  addition  to  the form ${name}, the forms $name
                  and $(name) are also recognized.  Specify $$  where
                  a single $ is wanted.

                  ${client_address}
                         This macro expands to the remote client net-
                         work address.

                         This is available in Postfix 2.2 and  later.

                  ${client_helo}
                         This macro expands to the remote client HELO
                         command parameter.

                         This is available in Postfix 2.2 and  later.

                  ${client_hostname}
                         This  macro  expands  to  the  remote client
                         hostname.

                         This is available in Postfix 2.2 and  later.

                  ${client_protocol}
                         This macro expands to the remote client pro-
                         tocol.

                         This is available in Postfix 2.2 and  later.

                  ${extension}
                         This  macro expands to the extension part of
                         a recipient address.  For example,  with  an
                         address  user+foo@domain  the  extension  is
                         foo.

                         A  command-line   argument   that   contains
                         ${extension}  expands  into as many command-
                         line arguments as there are recipients.

                         This information is modified by the  u  flag
                         for case folding.

                  ${mailbox}
                         This  macro  expands  to  the complete local
                         part of a recipient address.   For  example,
                         with  an address user+foo@domain the mailbox
                         is user+foo.

                         A  command-line   argument   that   contains
                         ${mailbox}  expands  to as many command-line
                         arguments as there are recipients.

                         This information is modified by the  u  flag
                         for case folding.

                  ${nexthop}
                         This macro expands to the next-hop hostname.

                         This information is modified by the  h  flag
                         for case folding.

                  ${recipient}
                         This macro expands to the complete recipient
                         address.

                         A  command-line   argument   that   contains
                         ${recipient} expands to as many command-line
                         arguments as there are recipients.

                         This information  is  modified  by  the  hqu
                         flags for quoting and case folding.

                  ${sasl_method}
                         This  macro  expands to the SASL authentica-
                         tion mechanism used during the reception  of
                         the  message.  An  empty string is passed if
                         the message has been received  without  SASL
                         authentication.

                         This  is available in Postfix 2.2 and later.

                  ${sasl_sender}
                         This macro expands to the SASL  sender  name
                         (i.e.  the  original  submitter  as  per RFC
                         2554) used during the reception of the  mes-
                         sage.

                         This  is available in Postfix 2.2 and later.

                  ${sasl_username}
                         This macro expands to  the  SASL  user  name
                         used during the reception of the message. An
                         empty string is passed if  the  message  has
                         been received without SASL authentication.

                         This  is available in Postfix 2.2 and later.

                  ${sender}
                         This macro expands to  the  envelope  sender
                         address. By default, the null sender address
                         expands  to  MAILER-DAEMON;  this   can   be
                         changed  with  the null_sender attribute, as
                         described above.

                         This information is modified by the  q  flag
                         for quoting.

                  ${size}
                         This  macro expands to Postfix's idea of the
                         message size, which is an  approximation  of
                         the size of the message as delivered.

                  ${user}
                         This macro expands to the username part of a
                         recipient address.   For  example,  with  an
                         address user+foo@domain the username part is
                         user.

                         A  command-line   argument   that   contains
                         ${user}  expands  into  as many command-line
                         arguments as there are recipients.

                         This information is modified by the  u  flag
                         for case folding.

    STANDARDS
           RFC 3463 (Enhanced status codes)

    DIAGNOSTICS
           Command  exit status codes are expected to follow the con-
           ventions defined in <sysexits.h>.   Exit  status  0  means
           normal successful completion.

           Postfix  version  2.3  and  later  support  RFC 3463-style
           enhanced status codes.  If a  command  terminates  with  a
           non-zero  exit  status, and the command output begins with
           an enhanced status code, this status code takes precedence
           over the non-zero exit status.

           Problems  and transactions are logged to syslogd(8).  Cor-
           rupted message files are marked so that the queue  manager
           can move them to the corrupt queue for further inspection.

    SECURITY
           This program needs a dual personality  1)  to  access  the
           private  Postfix  queue and IPC mechanisms, and 2) to exe-
           cute external commands as the specified user. It is there-
           fore security sensitive.

    CONFIGURATION PARAMETERS
           Changes  to main.cf are picked up automatically as pipe(8)
           processes run for only a limited amount of time.  Use  the
           command "postfix reload" to speed up a change.

           The  text  below  provides  only  a parameter summary. See
           postconf(5) for more details including examples.

    RESOURCE AND RATE CONTROLS
           In the text below, transport is the first field in a  mas-
           ter.cf entry.

           transport_destination_concurrency_limit ($default_destina-
           tion_concurrency_limit)
                  Limit the number of parallel deliveries to the same
                  destination, for delivery via the named  transport.
                  The limit is enforced by the Postfix queue manager.

           transport_destination_recipient_limit   ($default_destina-
           tion_recipient_limit)
                  Limit the number of recipients per  message  deliv-
                  ery,  for  delivery  via  the named transport.  The
                  limit is enforced by the Postfix queue manager.

           transport_time_limit ($command_time_limit)
                  Limit the time for delivery  to  external  command,
                  for delivery via the named transport.  The limit is
                  enforced by the pipe delivery agent.

    MISCELLANEOUS CONTROLS
           config_directory (see 'postconf -d' output)
                  The default location of  the  Postfix  main.cf  and
                  master.cf configuration files.

           daemon_timeout (18000s)
                  How  much time a Postfix daemon process may take to
                  handle a request  before  it  is  terminated  by  a
                  built-in watchdog timer.

           delay_logging_resolution_limit (2)
                  The  maximal  number  of  digits  after the decimal
                  point when logging sub-second delay values.

           export_environment (see 'postconf -d' output)
                  The list of environment variables  that  a  Postfix
                  process will export to non-Postfix processes.

           ipc_timeout (3600s)
                  The time limit for sending or receiving information
                  over an internal communication channel.

           mail_owner (postfix)
                  The UNIX system account that owns the Postfix queue
                  and most Postfix daemon processes.

           max_idle (100s)
                  The  maximum  amount  of  time that an idle Postfix
                  daemon process waits for the next  service  request
                  before exiting.

           max_use (100)
                  The  maximal number of connection requests before a
                  Postfix daemon process terminates.

           process_id (read-only)
                  The process ID  of  a  Postfix  command  or  daemon
                  process.

           process_name (read-only)
                  The  process  name  of  a Postfix command or daemon
                  process.

           queue_directory (see 'postconf -d' output)
                  The location of the Postfix top-level queue  direc-
                  tory.

           recipient_delimiter (empty)
                  The separator between user names and address exten-
                  sions (user+foo).

           syslog_facility (mail)
                  The syslog facility of Postfix logging.

           syslog_name (postfix)
                  The mail system  name  that  is  prepended  to  the
                  process  name  in  syslog  records, so that "smtpd"
                  becomes, for example, "postfix/smtpd".

    SEE ALSO
           qmgr(8), queue manager
           bounce(8), delivery status reports
           postconf(5), configuration parameters
           master(5), generic daemon options
           master(8), process manager
           syslogd(8), system logging

    LICENSE
           The Secure Mailer license must be  distributed  with  this
           software.

    AUTHOR(S)
           Wietse Venema
           IBM T.J. Watson Research
           P.O. Box 704
           Yorktown Heights, NY 10598, USA

                                                                           PIPE(8)