I too installed it at work and home and like the look. Haven't experienced the slowness issues either. I POP my mail though. I think I'm too dumb to use smart folders though. I still prefer the "All folders" view.
You can try modifying the send line like so:
>if(mail($to, $subject, $message, $headers -fsomeone@your-domain.ext)
Make sure someone@your-domain.ext is a valid email address for your domain.
What forum software is it? Have you checked the administration panel? Change the email address for the board administrator then set up a rule for any mail for that address to "discard the message" in cpanel under account level filters.