[Dovecot] Unoffical Survey - What MTA/Spam filtering do you use?

I like this unofficial survey of hardware but wondering what MTA and spam filtering everyone is using. I do front end spam filtering for other servers as well. (junkemailfilter.com)

I'm using Exim 4.61 SpamAssassin 3.11 Some version of DSpam that I'm experimenting with Most of my spam filtering happens on the Exim level.

My mail spam filter server is: AMD 3800 Dual Core Athlon 2 100gb SATA drives 4 gigs ram 64 bit Fedora Core 4

2 backup servers on higher MX recored that are similar configuration.