The ability to set some sort of parameters would be nice.
That ability is already in Mail. Between Junk Mail Behavior options and Rules with a little (maybe a lot) thought you should be able to create a fairly sophisticated custom set of behaviors for handling junk mail (a..k.a. spam). Unfortunately AOL may get in line ahead of Mail. I looked at AOL's instructions for handling spam, and it appears that it is geared toward using the webmail interface but it might be possible to pretty much turn their spam filtering off and let Mail do the heavy lifting.
