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REGEXP_TABLE(5)               File Formats Manual              REGEXP_TABLE(5)



NAME
       regexp_table - format of Postfix regular expression tables

SYNOPSIS
       regexp:/etc/postfix/filename

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

       postmap -q - 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.  Alterna-
       tively,  lookup  tables  can  be  specified in POSIX regular expression
       form.

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

       To test lookup tables, use the postmap command as described in the SYN-
       OPSIS above.

       The general form of a Postfix regular expression table is:

       /pattern/flags result

       !/pattern/flags result
              When pattern matches (does not match) a search string,  use  the
              corresponding result value.

       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.

       if /pattern/flags

       if !/pattern/flags

       endif  Match  the  search  string  against  the patterns between if and
              endif, if and only if the search string matches (does not match)
              pattern. The if..endif can nest.

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

       Each  pattern is a regular expression enclosed by a pair of delimiters.
       The regular  expression  syntax  is  described  in  re_format(7).   The
       expression delimiter can be any character, except whitespace or charac-
       ters that have special meaning  (traditionally  the  forward  slash  is
       used). The regular expression can contain whitespace.

       By default, matching is case-insensitive, although following the second
       slash with an `i' flag will reverse this. Other flags are `x'  (disable
       extended  expression syntax), and `m' (enable multi-line mode, that is,
       treat newline characters as special).

       Each pattern is applied to the entire lookup key 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  parent  network  search is done, and 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.

       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.

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
       /^To: friend@public\.com/       REJECT

EXAMPLE BODY FILTER MAP
       # First skip over base 64 encoded text to save CPU cycles.
       ~^[[:alnum:]+/]{60,}$~          OK

       # Put your own body patterns here.

SEE ALSO
       pcre_table(5) format of PCRE tables

AUTHOR(S)
       The regexp table lookup code was originally written by:
       LaMont Jones
       lamontAThp.com

       That code was based on the PCRE dictionary contributed by:
       Andrew McNamara
       andrewmATconnect.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)