Sometimes the various mechanisms to stop unwanted postings are
inapproriate for a list, or a royal pain.  (I have occasionally
gotten around addressing problems affecting some subscribers ability
to post to a send=PRIVATE list by setting SEND=PUBLIC.  Setting such
a list back to private is not possible unless the original problem
has gone away) In any case, a list owner can notify the offender that
the postings are not wanted.  If the postings continue, the list
owner should contact the site providing network access.  I know that
we would take action against anyone from who was ill-behaved, and I
know that other sites do so, as well.  I realize this will not work
in all cases, but for some it will.