I've always found it frustrating that guest comments were always sent from b2evo@mydomain.com (assume $notify_from;) ... so everytime I hit "reply", I'd only send myself a message. :p

I tracked down where this happens and was going to hack in

<?php 
$mail_from = $this->author_email;
?>

when I noticed that it's ALREADY SUPPOSED TO BE DOING THIS. :-/

Somehow ... $email must be empty. :o

My guess (and the reason I'm saying "bug") is that maybe $email needs to be globaled, prior to the test? ;)