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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 recursive.

       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_rewrite_clients   parameter,   or	 if   the
       remote_header_rewrite_domain  configuration  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.Last-
       name, or to clean up addresses produced by legacy mail systems.

       The  canonical(5)  mapping  is not to be confused with virtual alias support 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 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 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 precedence.

	      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.Lastname.

       @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 oth-
	      erdomain.

       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  exten-
       sion (+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 reg-
       exp_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  con-
       stituent 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 paren-
       thesized substrings from the pattern can be interpolated 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_ta-
       ble(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 constituent 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  propagate  an  address
	      extension from the original address to the result.  Specify zero or more of canoni-
	      cal, virtual, alias, forward, 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 mes-
	      sage  headers  from  other  clients  at  all, or rewrite message headers and update
	      incomplete addresses with the domain specified in the  remote_header_rewrite_domain
	      parameter.

       proxy_interfaces
	      Other interfaces that this machine receives mail on by way of a proxy agent or net-
	      work 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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