"Grumman-581" wrote:

What I want in a newsreader is the ability to filter messages that are
crossposted, expecially to groups to which I have no desire to read (e.g.
the NASCAR group in this crosspost)...

I don't know if any have that capability. What I use is a
no-longer-supported freeware program called NewsProxy (also known as
nfilter). It sits between your newsreader and your internet
connection, and applies rules to filter messages. Not the most
user-friendly software, but if you are moderately computer adept, you
can make it work. It's popular on another forum I participate in,
where one of the regulars keeps updating the rule set to get rid of
some of the noise in the forum. It might be what you are looking for.
Examples from his rule set include killing messages from known trolls
and spammers, troll indicators in the subject line, cross posts to
more than 3 groups or to particular irrelevant groups, while not
filtering out messages cross-posted to certain relevant groups.

Here's a source if you are interested:
http://www.nfilter.org

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Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently.