CANONICAL(5)                                                      CANONICAL(5)



NAME
       canonical - Postfix canonical table format

SYNOPSIS
       postmap /etc/postfix/canonical

       postmap -q "string" /etc/postfix/canonical

       postmap -q - /etc/postfix/canonical <inputfile

DESCRIPTION
       The  optional canonical(5) table specifies an address mapping for local
       and non-local addresses. The mapping is used by the cleanup(8)  daemon,
       before  mail  is  stored into the queue.  The address mapping is recur-
       sive.

       Normally, the canonical(5) 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  /etc/postfix/canonical"  to rebuild an
       indexed file after changing the corresponding 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  expressions,  or  lookups  can  be
       directed to TCP-based server. In those cases, the lookups are done in a
       slightly different way as described  below  under  "REGULAR  EXPRESSION
       TABLES" or "TCP-BASED TABLES".

       By  default  the  canonical(5)  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).  This  is  controlled  with  the  canonical_classes
       parameter.

       NOTE:  Postfix  versions  2.2  and  later  rewrite message headers from
       remote SMTP clients only if the  client  matches  the  local_header_re-
       write_clients parameter, or if the remote_header_rewrite_domain config-
       uration parameter specifies a non-empty  value.  To  get  the  behavior
       before    Postfix    2.2,   specify   "local_header_rewrite_clients   =
       static:all".

       Typically, one would use the canonical(5) table to replace login  names
       by Firstname.Lastname, or to clean up addresses produced by legacy mail
       systems.

       The canonical(5) mapping is not to be confused with virtual alias  sup-
       port  or  with  local  aliasing.  To change the destination but not the
       headers, use the virtual(5) or aliases(5) map instead.

CASE FOLDING
       The search string is folded to lowercase before database lookup. As  of
       Postfix  2.3,  the search string is not case folded with database types
       such as regexp: or pcre: whose lookup fields can match both  upper  and
       lower case.

TABLE FORMAT
       The input format for the postmap(1) command is as follows:

       pattern address
              When  pattern  matches  a mail address, replace it by the corre-
              sponding address.

       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 logical line.

TABLE SEARCH ORDER
       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
              Replace user@domain by address. This form has the highest prece-
              dence.

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

       user address
              Replace  user@site  by  address when site is equal to $myorigin,
              when site is listed in $mydestination, or when it is  listed  in
              $inet_interfaces or $proxy_interfaces.

              This form is useful for replacing login names by Firstname.Last-
              name.

       @domain address
              Replace other addresses in domain by address.  This form has the
              lowest precedence.

              Note:  @domain  is  a  wild-card.  When  this form is applied to
              recipient addresses, the Postfix SMTP server  accepts  mail  for
              any  recipient  in  domain, regardless of whether that recipient
              exists.  This may turn  your  mail  system  into  a  backscatter
              source:  Postfix  first accepts mail for non-existent recipients
              and then tries to return that mail  as  "undeliverable"  to  the
              often forged sender address.

RESULT ADDRESS REWRITING
       The lookup result is subject to address rewriting:

             When  the  result  has the form @otherdomain, the result becomes
              the same user in otherdomain.

             When "append_at_myorigin=yes", append "@$myorigin" to  addresses
              without "@domain".

             When "append_dot_mydomain=yes", append ".$mydomain" to addresses
              without ".domain".

ADDRESS EXTENSION
       When a mail address localpart contains the optional recipient delimiter
       (e.g.,  user+foo@domain),  the  lookup  order becomes: user+foo@domain,
       user@domain, user+foo, user, and @domain.

       The  propagate_unmatched_extensions  parameter  controls   whether   an
       unmatched address extension (+foo) is propagated 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 bro-
       ken 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 interpo-
       lated as $1, $2 and so on.

TCP-BASED TABLES
       This section describes how the table lookups change  when  lookups  are
       directed   to  a  TCP-based  server.  For  a  description  of  the  TCP
       client/server lookup protocol, see tcp_table(5).  This feature  is  not
       available up to and including Postfix version 2.4.

       Each  lookup operation uses the entire address once.  Thus, user@domain
       mail addresses are not broken up  into  their  user  and  @domain  con-
       stituent parts, nor is user+foo broken up into user and foo.

       Results are the same as with indexed file lookups.

BUGS
       The table format does not understand quoting conventions.

CONFIGURATION PARAMETERS
       The  following  main.cf  parameters  are especially relevant.  The text
       below provides only a  parameter  summary.  See  postconf(5)  for  more
       details including examples.

       canonical_classes
              What addresses are subject to canonical address mapping.

       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.

       propagate_unmatched_extensions
              A list of address rewriting or forwarding mechanisms that propa-
              gate an address extension  from  the  original  address  to  the
              result.  Specify zero or more of canonical, virtual, alias, for-
              ward, include, or generic.

       Other parameters of interest:

       inet_interfaces
              The network interface addresses that this system  receives  mail
              on.   You  need  to  stop  and start Postfix when this parameter
              changes.

       local_header_rewrite_clients
              Rewrite message header addresses in mail from these clients  and
              update incomplete addresses with the domain name in $myorigin or
              $mydomain; either  don't  rewrite  message  headers  from  other
              clients at all, or rewrite message headers and update incomplete
              addresses with the domain  specified  in  the  remote_header_re-
              write_domain parameter.

       proxy_interfaces
              Other  interfaces that this machine receives mail on by way of a
              proxy agent or network address translator.

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

       masquerade_domains
              List of domains that hide their subdomain structure.

       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.

       remote_header_rewrite_domain
              Don't  rewrite  message  headers from remote clients at all when
              this parameter is empty; otherwise, rewrite message headers  and
              append the specified domain name to incomplete addresses.

SEE ALSO
       cleanup(8), canonicalize and enqueue mail
       postmap(1), Postfix lookup table manager
       postconf(5), configuration parameters
       virtual(5), virtual aliasing

README FILES
       Use  "postconf readme_directory" or "postconf html_directory" to locate
       this information.
       DATABASE_README, Postfix lookup table overview
       ADDRESS_REWRITING_README, address rewriting guide

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



                                                                  CANONICAL(5)

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