I keep getting messages from "onenewsnow", some right-wing religous wacko group and it doesn't matter how many times I spam them, their messages keep appearing in my inbox (and it's annoying to get a "new message" notice when I'm expecting something important only for it to be this crap). I even went so far as to e-mail the site and request my e-mail be taken off their contact list but shocker shocker they haven't. EDIT: Using Yahoo mail, btw
Yahoo spam filter sucks. Try switching to gmail. You should be able to have your yahoo mail forwarded to gmail and let their filter sort it out.
Try this: Apply a filter. Make a new filter that says if it contains that keyword, move it to the trash.