On Sat, 17 Aug 2013 12:51:54 -0400, Joe Gwinn wrote:

There was a thread some time ago on ways to kill postings with too many
cross-posts. Some of these methods involved regular expressions, most
likely counting commas in the newsgroups header. Can anyone provide a
pointer to the thread, or related threads?

The third link in google for terms
newsgroup filter crosspost count
looks like an r.c.m thread from 31 Aug 2011,
subject = "Agent kill filter help please". See eg
https://groups.google.com/forum/#!topic/rec.crafts.metalworking/P_jb3KpxUaU

You could also add a term for your specific newsreader.

--
jiw