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) dae-
       mon, 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_re-
       write_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.Lastname, 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 recipi-
	      ent 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 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.

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 propagate an address extension from the original address to the result.
	      Specify zero or more of canonical, 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  message  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 network address translator.

       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.

       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)