    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 to create an indexed file for
           fast lookup.

           Execute the  command  "postmap  /etc/postfix/canonical"  to  rebuild  a
           default-type  indexed  file  after  changing  the text file, or execute
           "postmap type:/etc/postfix/canonical" to specify an explicit type.

           The default indexed file type  is  configured  with  the  default_data-
           base_type  parameter.  Depending  on  the  platform  this may be one of
           lmdb:, cdb:, hash:, or dbm: (without the trailing ':').

           When the table is provided via other means such as NIS,  LDAP  or  SQL,
           the same lookups are done as for ordinary indexed files.  Managing such
           databases is outside the scope of Postfix.

           Alternatively, the table can be provided as  a  regular-expression  map
           where  patterns  are  given  as  regular expressions, or lookups can be
           directed to a 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,  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-
                  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.

                  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 =
                          ...
                          reject_unauth_destination
                          check_recipient_access
                              inline:{example.com=reject_unverified_recipient}
                      unverified_recipient_reject_code = 550

                  In the above example, Postfix may contact a remote server if the
                  recipient is rewritten to a remote 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 (envelope_sender, envelope_recipient,  header_sender,
           header_recipient)
                  What addresses are subject to canonical_maps address mapping.

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

           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 local network interface  addresses  that  this  mail  system
                  receives mail on.

           local_header_rewrite_clients (permit_inet_interfaces)
                  Rewrite  or  add  message  headers  in  mail from these clients,
                  updating incomplete addresses with the domain name in  $myorigin
                  or $mydomain, and adding missing headers.

           proxy_interfaces (empty)
                  The  remote  network  interface  addresses that this mail system
                  receives mail on by way of a proxy or network  address  transla-
                  tion 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  addresses  match  $masquer-
                  ade_domains.

           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)
                  Rewrite  or  add  message headers in mail from remote clients if
                  the remote_header_rewrite_domain parameter value  is  non-empty,
                  updating  incomplete  addresses with the domain specified in the
                  remote_header_rewrite_domain parameter, and adding missing head-
                  ers.

    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

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

                                                                      CANONICAL(5)