If your newsreader handles regular expressions (regex) in its killfile
setup, set "if "newsgroup" contains" to:

([^,]+,){2,}

That will kill off any articles crossposted to 3 groups or more. Then
it's just a case of picking off the remaining couple of lunatics and
life is back to normal. I just checked the post nunbers for the past
couple of days: near 800, of which over 600 were crossposted garbage.

Dave.