[link|http://users.pandora.be/luc.vanbogaert/reviews/pronews.htm|ProNews/2] is an OS/2 product whose source "escaped" onto the Net. Trevor Helmsley (sp?) and others fixed some bugs with it. I only looked at it briefly, but it was very powerful. It might do what you need.
I'd think that a text-based reader like Yarn, possibly coupled with Soup or the like would do what you need. I think you can build kill/score files based on just about anything in the message and message-header. Rummage around the [link|http://www.vex.net/yarn/|Yarn] [link|http://www.vex.net/yarn/archive/|archive] and see what's appropriate. I used the OS/2 version with souper for many years. It's wonderful software. It's a shame that the author let it die without releasing the source...
[link|http://www.math.fu-berlin.de/~guckes/slrn/|slrn] also has a lot of fans. Ports are available for lots of OSes. I only briefly looked at it. It's probably the safer choice as it's still under development.
HTH.
Cheers,
Scott.