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REGEXP_TABLE(5)               File Formats Manual              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 expres-
       sion form. In this case, each input is compared against a list of  pat-
       terns.  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. Use "postmap -hmq - <file"  for  header_checks(5)  pat-
       terns,  and  "postmap -bmq - <file" for body_checks(5) (Postfix 2.6 and
       later).
COMPATIBILITY
       With Postfix version 2.2 and earlier specify "postmap -fq" to  query  a
       table that contains case sensitive patterns. Patterns are case insensi-
       tive 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 corre-
              sponding result value.
       if /pattern/flags
       endif  If the input string matches /pattern/,  then  match  that  input
              string against the patterns between if and endif.  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  If the input string does not match /pattern/,  then  match  that
              input  string  against  the  patterns  between if and endif. 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 delim-
       iters. 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  non-alphanumerical character,
       except whitespace or characters that have special  meaning  (tradition-
       ally  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 par-
       ent network search is done, and user@domain mail addresses are not bro-
       ken  up  into  their user and domain constituent parts, nor is user+foo
       broken up into user and foo.
TEXT SUBSTITUTION
       Substitution of substrings (text that  matches  patterns  inside  "()")
       from  the  matched  expression into the result string is requested with
       $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 AT hp.com
       That code was based on the PCRE dictionary contributed by:
       Andrew McNamara
       andrewm AT connect.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
       Wietse Venema
       Google, Inc.
       111 8th Avenue
       New York, NY 10011, USA

                                                               REGEXP_TABLE(5)