we remove "unknown" because the user never sees anything that distinguishes unknown from not junk. being left with just junk and not junk, we remove not junk, because that's just "isn't junk" r/sr=bienvenu, a=asa git-svn-id: svn://10.0.0.236/trunk@137224 18797224-902f-48f8-a5cc-f745e15eee43