CANONICAL(5)							File Formats Manual						      CANONICAL(5)

NAME

       canonical - format of Postfix canonical table

SYNOPSIS

       postmap /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 /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 expressions.  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 logical 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	produce  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 $mydestination, 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 @otherdomain, the result is the same user in otherdomain.

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.  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 regu-
       lar 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 inter-
       polated 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_recipient, header_sender, header_recipi-
	      ent.

       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.

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

																      CANONICAL(5)