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  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 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)