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GENERIC(5)                                                          GENERIC(5)



NAME
       generic - Postfix generic table format

SYNOPSIS
       postmap /etc/postfix/generic

       postmap -q "string(3,n)" /etc/postfix/generic

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

DESCRIPTION
       The optional generic(5) table specifies an address mapping that applies
       when mail(1,8) is delivered. This is the opposite of  canonical(5)  mapping,
       which applies when mail(1,8) is received.

       Typically, one would use the generic(5) table on a system that does not
       have a valid Internet domain name and that uses something like localdo-
       main.local  instead.   The generic(5) table is then used by the smtp(8)
       client to transform local  mail(1,8)  addresses  into  valid  Internet  mail(1,8)
       addresses  when mail(1,8) has to be sent across the Internet.  See the EXAM-
       PLE section at the end of this document.

       The generic(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(1,8) SMTP protocol commands).

       Normally, the generic(5) table is specified as a text file(1,n) that  serves
       as input to the postmap(1) command.  The result, an indexed file(1,n) in(1,8) dbm
       or db format, is used for fast searching by the  mail(1,8)  system.  Execute
       the  command  "postmap  /etc/postfix/generic"  in(1,8)  order to rebuild the
       indexed file(1,n) after changing the 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 that case, the lookups are done in(1,8) a
       slightly different way as described  below  under  "REGULAR  EXPRESSION
       TABLES" and "TCP-BASED TABLES".

TABLE FORMAT
       The input format for the postmap(1) command is as follows:

       pattern result
              When  pattern  matches  a mail(1,8) address, replace it by the corre-
              sponding 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(1,8) the order as
       listed below:

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

       user address
              Replace  user@site  by  address when site is equal to $myorigin,
              when site is listed in(1,8) $mydestination, or when it is  listed  in(1,8)
              $inet_interfaces or $proxy_interfaces.

       @domain address
              Replace other addresses in(1,8) domain by address.  This form has the
              lowest precedence.

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(1,8) 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(1,8) 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(1,8) 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(1,8) 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(1,8) the order as specified in(1,8) the  table,  until  a
       pattern is found that matches the search string.

       Results  are the same as with indexed file(1,n) 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(1,3,5) 2.2.

       Each lookup operation uses the entire address once.  Thus,  user@domain
       mail(1,8)  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(1,n) lookups.

EXAMPLE
       The following shows a generic mapping with an indexed file.  When  mail(1,8)
       is  sent to a remote host(1,5) via SMTP, this replaces his@localdomain.local
       by his ISP mail(1,8) address, replaces her@localdomain.local by her ISP mail(1,8)
       address, and replaces other local addresses by his ISP account, with an
       address extension of +local (this example assumes that the ISP supports
       "+" style address extensions).

       /etc/postfix/main.cf:
               smtp_generic_maps = hash:/etc/postfix/generic

       /etc/postfix/generic:
               his@localdomain.local   hisaccount@hisisp.example
               her@localdomain.local   heraccount@herisp.example
               @localdomain.local      hisaccount+local@hisisp.example

       Execute  the  command "postmap /etc/postfix/generic" whenever the table
       is changed.  Instead of hash, some systems use dbm database  files.  To
       find  out  what  tables  your system supports use the command "postconf(1,5)
       -m".

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(1,5)(5) for more
       details including examples.

       smtp_generic_maps
              Address mapping lookup table for envelope and header sender  and
              recipient addresses while delivering mail(1,8) via SMTP.

       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(5,8), alias, for-
              ward, include, or generic.

       Other parameters of interest:

       inet_interfaces
              The network interface addresses that this system  receives  mail(1,8)
              on.   You  need  to  stop  and start Postfix when this parameter
              changes.

       proxy_interfaces
              Other interfaces that this machine receives mail(1,8) on by way of  a
              proxy agent or network address translator.

       mydestination
              List of domains that this mail(1,8) 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.

SEE ALSO
       postmap(1), Postfix lookup table manager
       postconf(1,5)(5), configuration parameters
       smtp(8), Postfix SMTP client

README FILES
       Use  "postconf(1,5) readme_directory" or "postconf(1,5) html_directory" to locate
       this information.
       ADDRESS_REWRITING_README, address rewriting guide
       DATABASE_README, Postfix lookup table overview
       STANDARD_CONFIGURATION_README, configuration examples

LICENSE
       The Secure Mailer license must be distributed with this software.

HISTORY
       A genericstable feature appears in(1,8) the Sendmail MTA.

       This feature is available in(1,8) Postfix 2.2 and later.

AUTHOR(S)
       Wietse Venema
       IBM T.J. Watson Research
       P.O. Box 704
       Yorktown Heights, NY 10598, USA



                                                                    GENERIC(5)

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