Provided by: postfix_2.2.10-1_i386 bug

NAME

       regexp_table - format of Postfix regular expression tables

SYNOPSIS

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

       postmap -fq - 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  specified  in  POSIX   regular
       expression form. In this case, each input is compared against a list of
       patterns, and when  a  match  is  found  the  corresponding  result  is
       returned.

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

       To test lookup tables, use the "postmap -fq" command  as  described  in
       the SYNOPSIS above.

TABLE FORMAT

       The general form of a Postfix regular expression table is:

       /pattern/flags result
              When  pattern  matches  the  input string, use the corresponding
              result value.

       !/pattern/flags result
              When  pattern  does  not  match  the  input  string,   use   the
              corresponding result value.

       if /pattern/flags

       endif  Match  the  input  string  against  the  patterns between if and
              endif, if and only  if  that  same  input  string  also  matches
              pattern. The if..endif can nest.

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

       if !/pattern/flags

       endif  Match  the  input  string  against  the  patterns between if and
              endif, if and only if that same  input  string  does  not  match
              pattern. The if..endif can nest.

       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.

       Each  pattern  is  a  POSIX  regular  expression  enclosed by a pair of
       delimiters. The regular expression syntax is documented in re_format(7)
       with  4.4BSD,  in  regex(5)  with  Solaris, and in regex(7) with Linux.
       Other systems may use other document names.

       The expression delimiter can be any  character,  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, and newlines are not  treated
       as  special  characters. The behavior is controlled by flags, which are
       toggled by appending one or more of the following characters after  the
       pattern:

       i (default: on)
              Toggles  the case sensitivity flag. By default, matching is case
              insensitive.

       x (default: on)
              Toggles the extended expression syntax flag. By default, support
              for extended expression syntax is enabled.

       m (default: off)
              Toggle the multi-line mode flag. When this flag is on, the ^ and
              $ metacharacters match immediately after and immediately  before
              a  newline  character,  respectively, in addition to matching at
              the start and end of the input string.

TABLE SEARCH ORDER

       Patterns are applied in the order as specified in the  table,  until  a
       pattern is found that matches the input string.

       Each  pattern  is applied to the entire input 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.

TEXT SUBSTITUTION

       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.

       Note: since negated patterns (those preceded by !) return a result when
       the expression does not match,  substitutions  are  not  available  for
       negated patterns.

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

       postmap(1), Postfix lookup table manager
       pcre_table(5), format of PCRE tables
       cidr_table(5), format of CIDR tables

README FILES

       Use  "postconf readme_directory" or "postconf html_directory" to locate
       this information.
       DATABASE_README, Postfix lookup table overview

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)