Rupture has TMDA. You can use it to kill SPAM. Beware, it is not the easiest thing in the world. You will need a bit of UNIX knowledge (creating and editing files and running commands) and a bit of general savvy (Internet, Email terms and ideas). However, it can be a boon to you if you put some time into it.

First, read about the project at its website. Also read the FAQ.

Then, read Rupture TMDA Introduction.

Then, read Rupture TMDA (Incoming) Setup Instructions.

Then, read Rupture TMDA (Outgoing) Setup Instructions.
Outgoing filtering is optional, but it makes a lot of things easier. It allows you to send from dated or tagged addresses.

Then, read Rupture TMDA (Templates) Setup Instructions.
Template customization is optional, but it makes the experience more personal for your correspondents.

You can also see yesterday's Rupture SPAM Stats Report.

Feel free to email the admin with any specific questions etc.