Based on your question, it sounds to me like you are looking for a couple of different pieces of functionality.

First, you want to take your current implementation of a web-based email program, scrap it, and replace it with something new.

At its most basic level, this is something that is rather easily handled by the Mail::Sendmail package. A simple front-end UI is easy enough to toss together for it, and the docs for the package cover its basic functionality quite well.

Secondly, you're looking for something with white/blacklists, as well as spam monitoring. For this, you could do much worse than Mail::SpamAssassin. I use this package on my personal Linux systems to catch and classify my spam. One of the features I like best about it is the fact that it includes a Bayesian spam filter (note: both of the above links are good reads for those interested in the theory behind Bayesian spam filtering.)