Ubuntu Manpage: canonical - Postfix canonical table format

Provided by: postfix_3.1.0-3ubuntu0.4_amd64

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.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 address
              When pattern matches a mail address, replace it by the corresponding 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 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:

       •      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  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 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_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 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 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_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.

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

       Wietse Venema
       Google, Inc.
       111 8th Avenue
       New York, NY 10011, USA

                                                                                                    CANONICAL(5)