    PCRE_TABLE(5)                                       PCRE_TABLE(5)

    NAME
           pcre_table - format of Postfix PCRE tables

    SYNOPSIS
           pcre:/etc/postfix/filename

           postmap -q "string" pcre:/etc/postfix/filename

           postmap -q - pcre:/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 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.

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

           The general form of a PCRE table is:

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

           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.

           if /pattern/flags

           endif  Match   the  search  string  against  the  patterns
                  between if and endif, if and  only  if  the  search
                  string matches pattern. The if..endif can nest.

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

           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, 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.

           m (default: off)
                  Toggles the PCRE_MULTILINE 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 subject string.

           s (default: on)
                  Toggles the PCRE_DOTALL flag. When this flag is on,
                  the .  metacharacter matches the newline character.
                  With Postfix versions prior to 20020528,  The  flag
                  is off by default, which is inconvenient for multi-
                  line message header matching.

           x (default: off)
                  Toggles the pcre extended flag. When this  flag  is
                  on,  whitespace  in  the  pattern  (other than in a
                  character class) and characters between a # outside
                  a  character  class  and the next newline character
                  are ignored. An escaping backslash can be  used  to
                  include  a whitespace or # character as part of the
                  pattern.

           A (default: off)
                  Toggles the PCRE_ANCHORED flag.  When this flag  is
                  on,  the  pattern  is forced to be "anchored", that
                  is, it is constrained to match only at the start of
                  the  string  which  is being searched (the "subject
                  string"). This  effect  can  also  be  achieved  by
                  appropriate constructs in the pattern itself.

           E (default: off)
                  Toggles  the  PCRE_DOLLAR_ENDONLY  flag.  When this
                  flag is  on,  a  $  metacharacter  in  the  pattern
                  matches  only  at  the  end  of the subject string.
                  Without this flag, a dollar  also  matches  immedi-
                  ately before the final character if it is a newline
                  character (but not before any other newline charac-
                  ters).  This flag is ignored if PCRE_MULTILINE flag
                  is set.

           U (default: off)
                  Toggles the ungreedy matching flag.  When this flag
                  is  on,  the  pattern  matching  engine inverts the
                  "greediness" of the quantifiers so  that  they  are
                  not  greedy  by  default, but become greedy if fol-
                  lowed by "?".  This flag can also  set  by  a  (?U)
                  modifier within the pattern.

           X (default: off)
                  Toggles the PCRE_EXTRA flag.  When this flag is on,
                  any backslash in a pattern that is  followed  by  a
                  letter that has no special meaning causes an error,
                  thus reserving these combinations for future expan-
                  sion.

           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

    EXAMPLE BODY FILTER MAP
           # First skip over base 64 encoded text to save CPU cycles.
           # Requires PCRE version 3.
           ~^[[:alnum:]+/]{60,}$~          OK

           # Put your own body patterns here.

    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

                                                        PCRE_TABLE(5)