Make sure that your Welcome Message has a clear focus -- stating
what kind of discussions are welcomed, as well as those kind that
are not.
 
Though perhaps not a good idea, you might want to consider changing
a mail distribution options to
 
           reply-to= sender
 
(This will have certain side effects, like how VAX VMS users scan
their new mail.)
 
Then, their is contact with their site administrators, assuming they
belong to some higher education institution.  Certainly bozo postings
give those institutions a certain reputation.
 
Computers and Academic Freedom is a whole career path for some Useneters.
I don't know if lstown-l can do it more justice.
 
The following listserv lists-of-lists search, when sent to
listserv@ndsuvm1 (@vm1.nodak.edu) will provide pointers to
some Internet lists.  I believe discussion is archived.
 
//ListSrch JOB Echo=no
Database Search DD=Rules
//Rules DD *
search * in lists where title contains (computer and freedom)
index list.8 node.8 title.62
search (computer and freedom) in new-list where subject does not -
 contain list-of-list
print
search (computer and freedom) in intgroup
print
/*