Simon Cozens

NAME

Email::Received - Parse an email Received: header

SYNOPSIS

  use Email::Received;

  for ($mail->header("Received")) {
    my $data = parse_received($_);
    return "SPAM" if rbl_lookup($data->{ip});
  }

DESCRIPTION

This module is a Perl Email Project rewrite of SpamAssassin's email header parser. We did this so that the great work they did in analysing pretty much every possible Received header format could be used in applications other than SpamAssassin itself.

The module provides one function, parse_received, which takes a single Received line. It then produces either nothing, if the line is unparsable, a hash reference like this:

    { reason => "gateway noise" }

if the line should be ignored for some good reason, and one like this:

   { ip => '64.12.136.4', id => '875522', by => 'xxx.com',
     helo => 'imo-m01.mx.aol.com' }

if it parsed the message. Possible keys are:

    ip rdns helo ident envfrom auth by id

RULE FORMAT

Where SpamAssassin used a big static subroutine full of regular expressions to parse the data, we build up a big subroutine full of regular expressions dynamically from a set of rules. The rules are stored at the bottom of this module. The basic format for a rule looks like this:

    ((var=~)?/REGEXP/)? [ACTION; ]+

The ACTION is either SET variable = $value, IGNORE "reason"?, UNPARSABLE or DONE.

One control structure is provided, which is basically an if statement:

    GIVEN (NOT)? /REGEXP/ {
        ACTION+
    }

EXPORT

parse_received

SEE ALSO

Mail::SpamAssassin::Message::Metadata::Received, from which the rules and some of the IP address matching constants were blatantly stolen. Thanks, guys, for doing such a comprehensive job!

AUTHOR

simon, <simon@>

COPYRIGHT AND LICENSE

Copyright (C) 2006 by simon

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.7 or, at your option, any later version of Perl 5 you may have available.