CANONICAL(5)		      File Formats Manual		  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 result
	      When  pattern  matches  a mail address, replace it by the corre-
	      sponding 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 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:

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

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

       o      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)