Rupture has procmail. You can use it to filter incoming email. 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 general savvy (Internet, Email terms and ideas). However, it can be a boon to you if you put some time into it.

What is Procmail?
Procmail is a mail processing utility which can help you filter your mail. It lets you sort incoming mail according to sender, Subject line, length of message, keywords in the message, etc.

How do I set it up?
Read Rupture Procmail (Including TMDA) Setup Instructions.

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