For those who have shell access, procmail can be used to do this. I know Panix has it, so it could even be set up to delete these posts before they're distributed to the list.
Entering the command man procmailsc at the unix prompt yields much information about procmail weighted averaging, of which this is only a small part--
If you are subscribed to a mailinglist, and just would like
to read the quality mails, then the following recipes could
do the trick. First we make sure that the mail is coming
from the mailinglist. Then we check if it is from certain
persons of whom we value the opinion, or about a subject we
absolutely want to know everything about. If it is, file
it. Otherwise, check if the ratio of quoted lines to origi-
nal lines is at most 1:2. If it exceeds that, ditch the
mail. Everything that survived the previous test, is filed.
:0
^From mailinglist-request at some.where
{
:0:
* ^(From:.*(paula|bill)|Subject:.*skiing)
mailinglist
:0 Bh
* 20^1 ^>
* -10^1 ^[^>]
/dev/null
:0:
mailinglist
}
-- Steven Matthews