[Mimedefang] Bouncing Dead Users?

[Frito]

I currently have an MD,SA,Rzr2 gateway filtering all incoming mail.  My
problem is that all spam aimed at ex-employees is getting redirected to my
spamdrop.  Does anyone know a quick way to make a list of addresses that
will get bounced at the server?  I've been trying to learn perl so I can
do it without help but it's not going too well.

Thanks,
Josh