Provided by: postfix_2.5.5-1_i386 bug

NAME

       regexp_table - format of Postfix regular expression tables

SYNOPSIS

       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,
       mail routing, or access control. 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.  When  a match is found, the corresponding result is returned
       and the search is terminated.

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

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

COMPATIBILITY

       With Postfix version 2.2 and earlier specify "postmap -fq" to  query  a
       table   that  contains  case  sensitive  patterns.  Patterns  are  case
       insensitive by default.

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.

              This feature is available in Postfix 2.1 and later.

       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.

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

              This feature is available in Postfix 2.1 and later.

       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.

       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.

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

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.;  specify  $$  to  produce  a  $
       character  as  output.   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)