    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 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 address
                  When  pattern  matches  a mail address, replace it by the corre-
                  sponding 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 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
           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)