RULES a

($id)\@($id)==><a href="mailto:$1\@\@$2">$1\@\@$2</a>

RULES b

\@\@==>\@

ENDRULES

$id='[\w_.-]+';
while(<>){print b(a($_))}

=head1

substitutes the emails with html links.

Tricks used:

 ($id)\@($id)==><a href=mailto:$1\@$2...

would give an infinite loop. We changed the @ in order to avoid it.