REGEXP_TABLE(5)                                   REGEXP_TABLE(5)

NAME
       regexp_table - format of Postfix regular expression tables

SYNOPSIS
       regexp:/usr/local/etc/postfix/filename

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  speci-
       fied in POSIX regular expression form.

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

       The general form of a Postfix regular expression table is:

       pattern result
              When  pattern matches a search string, use the cor-
              responding 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 logi-
              cal line.

       pattern1!pattern2 result
              Matches pattern1 but not pattern2.

       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 charac-
       ter,  except  whitespace  or  characters that have special
       meaning (traditionally the forward  slash  is  used).  The
       regular expression can contain whitespace.

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

       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
       /^(.*)-outgoing@(.*)$/!/^owner-/         550 Use ${1}@${2} instead

EXAMPLE HEADER FILTER MAP
       # These were once common in junk mail.
       /^Subject: make money fast/     REJECT
       /^To: friend@public\.com/       REJECT

SEE ALSO
       pcre_table(5) format of PCRE tables

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

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