SYNOPSIS

       postmap -fq "string" regexp:/etc/postfix/filename

       postmap -fq - regexp:/etc/postfix/filename <inputfile

DESCRIPTION

       The  Postfix  mail system uses optional tables for address rewriting or
       mail routing. These tables are usually in dbm or db format.

       Alternatively, lookup tables can be specified in POSIX regular  expres-
       sion  form. In this case, each input is compared against a list of pat-
       terns, and when a match is found the corresponding result is  returned.

       To  find  out  what types of lookup tables your Postfix system supports
       use the postconf -m command.

       To test lookup tables, use the postmap -fq command as described in  the
       SYNOPSIS above.

TABLE FORMAT

       The general form of a Postfix regular expression table is:

       /pattern/flags result
              When  pattern  matches  the  input string, use the corresponding
              result value.

       !/pattern/flags result
              When pattern does not match the input  string,  use  the  corre-
              sponding result value.

       if /pattern/flags

       endif  Match  the  input  string  against  the  patterns between if and
              endif, if and only if that same input string also  matches  pat-
              tern. The if..endif can nest.

              Note: do not prepend whitespace to patterns inside if..endif.

       if !/pattern/flags

       endif  Match  the  input  string  against  the  patterns between if and
              endif, if and only if that same input string does not match pat-
              tern. The if..endif can nest.

       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.

       i (default: on)
              Toggles  the case sensitivity flag. By default, matching is case
              insensitive.

       x (default: on)
              Toggles the extended expression syntax flag. By default, support
              for extended expression syntax is enabled.

       m (default: off)
              Toggle the multi-line mode flag. When this flag is on, the ^ and
              $ metacharacters match immediately after and immediately  before
              a  newline  character,  respectively, in addition to matching at
              the start and end of the input string.

TABLE SEARCH ORDER

       Patterns are applied in the order as specified in the  table,  until  a
       pattern is found that matches the input string.

       Each  pattern  is applied to the entire input string.  Depending on the
       application, that string is an entire client hostname, an entire client
       IP  address, or an entire mail address.  Thus, no parent domain or par-
       ent network search is done, and 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.

TEXT SUBSTITUTION

       Substitution of substrings from the matched expression into the  result
       string  is possible using $1, $2, etc.. The macros in the result string
       may need to be written as ${n} or  $(n)  if  they  aren't  followed  by
       whitespace.

       Note: since negated patterns (those preceded by !) return a result when
       the expression does not match,  substitutions  are  not  available  for
       negated patterns.

EXAMPLE SMTPD ACCESS MAP

       # Disallow sender-specified routing. This is a must if you relay mail
       # for other domains.
       /[%!@].*[%!@]/       550 Sender-specified routing rejected

       # Postmaster is OK, that way they can talk to us about how to fix
       # their problem.
       /^postmaster@/       OK

       # Protect your outgoing majordomo exploders
       if !/^owner-/
       /^(.*)-outgoing@(.*)$/   550 Use ${1}@${2} instead
       endif

EXAMPLE HEADER FILTER MAP

       # These were once common in junk mail.
       /^Subject: make money fast/     REJECT
       Use  "postconf readme_directory" or "postconf html_directory" to locate
       this information.
       DATABASE_README, Postfix lookup table overview

AUTHOR(S)

       The regexp table lookup code was originally written by:
       LaMont Jones
       lamont@hp.com

       That code was based on the PCRE dictionary contributed by:
       Andrew McNamara
       andrewm@connect.com.au
       connect.com.au Pty. Ltd.
       Level 3, 213 Miller St
       North Sydney, NSW, Australia

       Adopted and adapted by:
       Wietse Venema
       IBM T.J. Watson Research
       P.O. Box 704
       Yorktown Heights, NY 10598, USA



                                                               REGEXP_TABLE(5)