    PCRE_TABLE(5)                                       PCRE_TABLE(5)

    NAME
           pcre_table - format of Postfix PCRE tables

    SYNOPSIS
           pcre:/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 Perl Compatible 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 PCRE table is:

           pattern result
                  When  pattern matches a search string, use the cor-
                  responding result.

           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  perl-like  regular  expression.  The
           expression  delimiter can be any character, except whites-
           pace 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, although follow-
           ing  the  second slash with an `i' flag will reverse this.
           Other flags are supported, but the only other  useful  one
           is `U', which makes matching ungreedy (see PCRE documenta-
           tion and source for more info).

           Each pattern is applied to the entire lookup  key  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.

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

           Substitution of substrings  from  the  matched  expression
           into  the result string is possible using the conventional
           perl syntax ($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.

    EXAMPLE SMTPD ACCESS MAP
           # Protect your outgoing majordomo exploders
           /^(?!owner-)(.*)-outgoing@/     550 Use ${1}@${2} instead

           # Bounce friend@whatever, except when whatever is our domain (you would
           # be better just bouncing all friend@ mail - this is just an example).
           /^friend@(?!my\.domain)/        550 Stick this in your pipe $0

           # A multi-line entry. The text is sent as one line.
           #
           /^noddy@my\.domain$/
            550 This user is a funny one. You really don't want to send mail to
            them as it only makes their head spin.

    EXAMPLE HEADER FILTER MAP
           /^Subject: make money fast/     REJECT
           /^To: friend@public\.com/       REJECT

    SEE ALSO
           regexp_table(5) format of POSIX regular expression tables

    AUTHOR(S)
           The PCRE table lookup code was originally written 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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