please consider incorporating DSPAM or CRM114 into cpanel.
from CRM114's website:
News Flash: As of Feb 1 through Feb 21, 2004, 6000+ messages, my total error rate was ONE. That translates to better than 99.984% accuracy, which is ten times more accurate than human accuracy (which I've measured to be around 99.84%. Current filtering speed is about 120 kbyte/sec for a moderate (P-iii 1.4 GHz) mailserver.
Old News: New hackery gives us a tremendous speedup- we're now running about 4 times faster than SpamAssassin while still retaining our high ( better than 99.9% ) accuracy after training. From Sep. 1 through 14 2003, I had ZERO errors on over 2500 emails on my live incoming email stream.
I plan on looking at installing this on my cpanel server, but it would be nice to see this incorporated in future versions.