Ubuntu Manpage: generic - Postfix generic table format

NAME

       generic - Postfix generic table format

SYNOPSIS

       postmap /etc/postfix/generic

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

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

DESCRIPTION

The optional generic(5) table specifies an address mapping that applies when mail is
delivered. This is the opposite of canonical(5) mapping, which applies when mail 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 localdomain.local instead. The
generic(5) table is then used by the smtp(8) client to transform local mail addresses into
valid Internet mail addresses when mail has to be sent across the Internet. See the
EXAMPLE 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 SMTP protocol commands).

Normally, the generic(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/generic" 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 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".

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

       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.

       @domain address
              Replace other addresses in 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
              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 available in Postfix 2.5 and later.

       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.

EXAMPLE

       The following shows a generic mapping with an indexed file.  When mail is sent to a remote
       host  via  SMTP,  this  replaces  his@localdomain.local  by his ISP mail address, replaces
       her@localdomain.local by her ISP mail 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 -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(5) for more details including examples.

smtp_generic_maps (empty)
Optional lookup tables that perform address rewriting in the Postfix SMTP client,
typically to transform a locally valid address into a globally valid address when
sending mail across the Internet.

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.

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

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 listname-request address localparts when the
recipient_delimiter is set to "-".

README FILES

       Use "postconf readme_directory" or "postconf 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 the Sendmail MTA.

       This feature is available in Postfix 2.2 and later.

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

                                                                                       GENERIC(5)