Is your problem-poster following the guidelines set forth in
your welcome file?  Is (s)he following the rules of your
list host's institution and network i.e., AUPs?
 
If not, then FILTER= is appropriate.
 
It is not clear to me that your computer and networking facilities MUST
be allowed to be used by others (who have no legal right to your
resources).  You are under no contractual agreement (?) and I presume
that the user has no affiliation with the hosting institution.
 
I'm sure the management at UBVM cuuld give you further guidance
into the particulars, ifs/ands/ors/buts.
 
--  co-owner INFOSYS, TQM-L, CPARK-L, ERAPPA-L, JANITORS, LDBASE-L, et -L
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