REGEXP_TABLE(5)                                   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. 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.

       To  test  lookup  tables,  use  the  postmap  command   as
       described in the SYNOPSIS 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  logi-
              cal line.

       if /pattern/flags

       if !/pattern/flags

       endif  Examine the lines between if..endif only if pattern
              matches (does not match). The if..endif  can  nest.
              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 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, 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
       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)