CANONICAL(5)                                                      CANONICAL(5)

       canonical - Postfix canonical table format

       postmap /etc/postfix/canonical

       postmap -q "string" /etc/postfix/canonical

       postmap -q - /etc/postfix/canonical <inputfile

       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-

       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

       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

       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   =

       Typically, one would use the canonical(5) table to replace login  names
       by Firstname.Lastname, or to clean up addresses produced by legacy mail

       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.

       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.

       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.

       With lookups from indexed files such as DB or DBM,  or  from  networked
       tables  such  as  NIS,  LDAP  or SQL, each user@domain query produces a
       sequence of query patterns as described below.

       Each query pattern is sent to each specified lookup table before trying
       the next query pattern, until a match is found.

       user@domain address
              Replace user@domain by address. This form has the highest prece-

              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-

       @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.

              To avoid backscatter with mail for a wild-card  domain,  replace
              the  wild-card  mapping  with  explicit  1:1  mappings, or add a
              reject_unverified_recipient restriction for that domain:

                  smtpd_recipient_restrictions =
                  unverified_recipient_reject_code = 550

              In the above example, Postfix may contact a remote server if the
              recipient is rewritten to a remote address.

       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".

       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

       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.

       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.

       The table format does not understand quoting conventions.

       The  following  parameters  are especially relevant.  The text
       below provides only a  parameter  summary.  See  postconf(5)  for  more
       details including examples.

       canonical_classes  (envelope_sender, envelope_recipient, header_sender,
              What addresses are subject to canonical_maps address mapping.

       canonical_maps (empty)
              Optional  address  mapping lookup tables for message headers and

       recipient_canonical_maps (empty)
              Optional address mapping lookup tables for envelope  and  header
              recipient addresses.

       sender_canonical_maps (empty)
              Optional  address  mapping lookup tables for envelope and header
              sender addresses.

       propagate_unmatched_extensions (canonical, virtual)
              What address lookup tables copy an address  extension  from  the
              lookup key to the lookup result.

       Other parameters of interest:

       inet_interfaces (all)
              The  network  interface addresses that this mail system receives
              mail on.

       local_header_rewrite_clients (permit_inet_interfaces)
              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 (empty)
              The  network  interface addresses that this mail system receives
              mail on by way of a proxy or network address translation unit.

       masquerade_classes (envelope_sender, header_sender, header_recipient)
              What addresses are subject to address masquerading.

       masquerade_domains (empty)
              Optional list of  domains  whose  subdomain  structure  will  be
              stripped off in email addresses.

       masquerade_exceptions (empty)
              Optional  list  of  user names that are not subjected to address
              masquerading,  even  when  their   address   matches   $masquer-

       mydestination ($myhostname, localhost.$mydomain, localhost)
              The  list of domains that are delivered via the $local_transport
              mail delivery transport.

       myorigin ($myhostname)
              The domain name that locally-posted mail appears to  come  from,
              and that locally posted mail is delivered to.

       owner_request_special (yes)
              Enable  special  treatment  for  owner-listname  entries  in the
              aliases(5)  file,  and  don't  split  owner-listname  and  list-
              name-request  address localparts when the recipient_delimiter is
              set to "-".

       remote_header_rewrite_domain (empty)
              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.

       cleanup(8), canonicalize and enqueue mail
       postmap(1), Postfix lookup table manager
       postconf(5), configuration parameters
       virtual(5), virtual aliasing

       DATABASE_README, Postfix lookup table overview
       ADDRESS_REWRITING_README, address rewriting guide

       The Secure Mailer license must be distributed with this software.

       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