    CANONICAL(5)                                         CANONICAL(5)

    NAME
           canonical - format of Postfix canonical table

    SYNOPSIS
           postmap /usr/local/etc/postfix/canonical

    DESCRIPTION
           The  optional canonical table specifies an address mapping
           for local and non-local addresses. The mapping is used  by
           the  cleanup(8) daemon.  The address mapping is recursive.

           Normally, the canonical table is specified as a text  file
           that  serves  as  input  to  the  postmap(1) command.  The
           result, an indexed file in dbm or db format, is  used  for
           fast  searching  by  the  mail system. Execute the command
           postmap /usr/local/etc/postfix/canonical in  order  to  rebuild  the
           indexed file after changing the text file.

           When  the  table  is provided via other means such as NIS,
           LDAP or SQL, the same lookups are  done  as  for  ordinary
           indexed files.

           Alternatively,  the  table  can  be provided as a regular-
           expression map where patterns are given as regular expres-
           sions.  In  that  case, the lookups are done in a slightly
           different way as described below.

           The  canonical  mapping  affects   both   message   header
           addresses (i.e. addresses that appear inside messages) and
           message envelope addresses  (for  example,  the  addresses
           that  are  used in SMTP protocol commands). Think Sendmail
           rule set S3, if you like.

           Typically, one would use the canonical  table  to  replace
           login   names   by  Firstname.Lastname,  or  to  clean  up
           addresses produced by legacy mail systems.

           The canonical mapping is not to be confused  with  virtual
           domain support. Use the virtual(5) map for that purpose.

           The  canonical  mapping  is  not to be confused with local
           aliasing.  Use the aliases(5) map for that purpose.

    TABLE FORMAT
           The format of the canonical table is as follows:

           pattern result
                  When pattern matches a mail address, replace it  by
                  the corresponding result.

           blank lines and comments
                  Empty  lines and whitespace-only lines are ignored,
                  as are lines whose first  non-whitespace  character
                  is a `#'.

           multi-line text
                  A  logical  line starts with non-whitespace text. A
                  line that starts with whitespace continues a  logi-
                  cal line.

           With lookups from indexed files such as DB or DBM, or from
           networked tables such as NIS, LDAP or  SQL,  patterns  are
           tried in the order as listed below:

           user@domain address
                  user@domain  is  replaced by address. This form has
                  the highest precedence.

                  This form useful to clean up addresses produced  by
                  legacy  mail  systems.  It can also be used to pro-
                  duce Firstname.Lastname style  addresses,  but  see
                  below for a simpler solution.

           user address
                  user@site is replaced by address when site is equal
                  to $myorigin, when site is  listed  in  $mydestina-
                  tion, or when it is listed in $inet_interfaces.

                  This  form  is  useful for replacing login names by
                  Firstname.Lastname.

           @domain address
                  Every address in domain  is  replaced  by  address.
                  This form has the lowest precedence.

           In  all the above forms, when address has the form @other-
           domain, the result is the same user in otherdomain.

    ADDRESS EXTENSION
           When a mail address localpart contains the optional recip-
           ient  delimiter  (e.g., user+foo@domain), the lookup order
           becomes: user+foo@domain, user@domain, user+foo, user, and
           @domain.   An unmatched address extension (+foo) is propa-
           gated to the result of table lookup.

    REGULAR EXPRESSION TABLES
           This section describes how the table lookups  change  when
           the table is given in the form of regular expressions. For
           a description of regular expression lookup  table  syntax,
           see regexp_table(5) or pcre_table(5).

           Each  pattern  is  a regular expression that is applied to
           the entire address being looked up. Thus, user@domain mail
           addresses  are  not  broken up into their user and @domain
           constituent parts, nor is user+foo broken up into user and
           foo.

           Patterns  are  applied  in  the  order as specified in the
           table, until a pattern is found that  matches  the  search
           string.

           Results  are  the  same as with indexed file lookups, with
           the additional feature that parenthesized substrings  from
           the pattern can be interpolated as $1, $2 and so on.

    BUGS
           The  table format does not understand quoting conventions.

    CONFIGURATION PARAMETERS
           The following main.cf parameters are  especially  relevant
           to  this  topic.  See  the Postfix main.cf file for syntax
           details and for default values.  Use  the  postfix  reload
           command after a configuration change.

           canonical_maps
                  List of canonical mapping tables.

           recipient_canonical_maps
                  Address  mapping  lookup  table  for  envelope  and
                  header recipient addresses.

           sender_canonical_maps
                  Address  mapping  lookup  table  for  envelope  and
                  header sender addresses.

           Other parameters of interest:

           inet_interfaces
                  The  network  interface  addresses that this system
                  receives mail on.

           masquerade_classes
                  List of address classes  subject  to  masquerading:
                  zero  or  more of envelope_sender, envelope_recipi-
                  ent, header_sender, header_recipient.

           masquerade_domains
                  List of domains that hide  their  subdomain  struc-
                  ture.

           masquerade_exceptions
                  List  of user names that are not subject to address
                  masquerading.

           mydestination
                  List of domains that  this  mail  system  considers
                  local.

           myorigin
                  The domain that is appended to locally-posted mail.

           owner_request_special
                  Give special treatment to owner-xxx and xxx-request
                  addresses.

    SEE ALSO
           cleanup(8) canonicalize and enqueue mail
           postmap(1) create mapping table
           virtual(5) virtual domain mapping
           pcre_table(5) format of PCRE tables
           regexp_table(5) format of POSIX regular expression tables

    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

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