=head1 NAME

Mail::Filter - Filter mail through multiple subroutines

=head1 SYNOPSIS

 use Mail::Filter;
    
 my $filter = Mail::Filter->new( \&filter1, \&filter2 );
    
 my $mail   = Mail::Internet->new( [<>] );
 my $mail   = $filter->filter($mail);

 my $folder = Mail::Folder->new( .... );
 my $filter->filter($folder);

=head1 DESCRIPTION

C<Mail::Filter> provides an interface to filtering Email through multiple
subroutines.

C<Mail::Filter> filters mail by calling each filter subroutine in turn. Each
filter subroutine is called with two arguments, the first is the filter
object and the second is the mail or folder object being filtered.

The result from each filter sub is passed to the next filter as the mail
object. If a filter subroutine returns undef, then C<Mail::Filter> will abort
and return immediately.

The function returns the result from the last subroutine to operate on the 
mail object.  

=head1 METHODS

=head2 Constructors

=over 4

=item Mail::Filter-E<gt>B<new>([FILTER [, ... ]])

Create a new C<Mail::Filter> object with the given filter subroutines. Each
filter may be either a code reference or the name of a method to call
on the <Mail::Filter> object.

=back

=head2 Accessors

=over 4

=item $obj-E<gt>B<add>(FILTER [, FILTER ...])

Add the given filters to the end of the fliter list.

=back

=head2 Processing

=over 4

=item $obj-E<gt>B<filter>(MAIL-OBJECT | MAIL-FOLDER)

If the first argument is a C<Mail::Internet> object, then this object will
be passed through the filter list. If the first argument is a C<Mail::Folder>
object, then each message in turn will be passed through the filter list.

=item $obj-E<gt>B<folder>

While the C<filter> method is called with a C<Mail::Folder> object, these
filter subroutines can call this method to obtain the folder object that is
being processed.

=item $obj-E<gt>B<msgnum>

If the C<filter> method is called with a C<Mail::Folder> object, then the
filter subroutines may call this method to obtain the message number
of the message that is being processed.

=back

=head1 SEE ALSO

This module is part of the MailTools distribution,
F<http://perl.overmeer.net/mailtools/>.

=head1 AUTHORS

The MailTools bundle was developed by Graham Barr.  Later, Mark
Overmeer took over maintenance without commitment to further development.

Mail::Cap by Gisle Aas E<lt>aas@oslonett.noE<gt>.
Mail::Field::AddrList by Peter Orbaek E<lt>poe@cit.dkE<gt>.
Mail::Mailer and Mail::Send by Tim Bunce E<lt>Tim.Bunce@ig.co.ukE<gt>.
For other contributors see ChangeLog.

=head1 LICENSE

Copyrights 1995-2000 Graham Barr E<lt>gbarr@pobox.comE<gt> and
2001-2007 Mark Overmeer E<lt>perl@overmeer.netE<gt>.

This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
See F<http://www.perl.com/perl/misc/Artistic.html>

