REGEXP_TABLE(5)                                                REGEXP_TABLE(5)

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 com-
       pared 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  sys-
       tem 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 cor-
              responding 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.
              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.

       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.

       Each pattern is a POSIX regular expression enclosed  by  a
       pair of delimiters. The regular expression syntax is docu-
       mented 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 (tradi-
       tionally the forward slash is used). The  regular  expres-
       sion can contain whitespace.

       By default, matching is case-insensitive, and newlines are
       not treated as special characters. The  behavior  is  con-
       trolled  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 ta-
       ble, 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
       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)