Knews question

[John Aldrich]

How does one, using KNEWS, do a bulk delete of "junk"
messages, leaving only the "core" message that you want to
keep? I mean, there's a TON of junk messages ("make money
fast", "come visit our porno site," etc) in the newsgroups.
I don't mind manually tagging them for deletion, but I find
no way to tell KNews to delete everything that's tagged, or
delete everything that is NOT tagged. I don't mind doing
either one of those, I just can't find that setting
anywhere!
        Thanks...
        John