I should probably use gnus-newsgroup-unseen rather than
gnus-newsgroup-articles.  But for a first pass, this appears to at
least be close.

> I don't think there's a way to automatically find out if a group is
> not a mail group, is there?

I actually only care about a single backend, which is easier to
check.  You can check if something is news or not (gnus-news-group-p),
at least.

-- 
David Maze             dmaze@mit.edu          http://www.mit.edu/~dmaze/
"Theoretical politics is interesting.  Politicking should be illegal."
	-- Abra Mitchell