REGEXP_TABLE(5)                                   REGEXP_TABLE(5)


NAME
       regexp_table - format of Postfix regular expression tables

SYNOPSIS
       regexp:/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:

       blanks and comments
              Blank  lines  are  ignored,  as are lines beginning
              with `#'.

       leading whitespace
              Lines that begin with whitespace continue the  pre-
              vious line.

       pattern result
              When  pattern matches a search string, use the cor-
              responding result. A line that  starts  with  white
              space continues the preceding 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 string being looked
       up.  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



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REGEXP_TABLE(5)                                   REGEXP_TABLE(5)


       table, until a pattern is found that  matches  the  search
       string.

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

EXAMPLES
       # 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

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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