Perhaps LISTSERV does not have to do much to recognize troublemaking mail.
If the FROM: address is non-conforming it should never be taken for commands
or distributed on a list.  The next question is what is non-conforming?
 
My opinion: if it has any character not permitted by the appropriate RFC's,
then it is non-conforming.  That can probably eliminate the majority.
 
As long as there are renegade and charlatan mail systems out there, life will
be tough, but I don't see why we have to submit to it if it makes our work
harder.  I see no reason why Eric or anyone else should have to go out of
their way to handle and process WRONGLY formatted mail.  I say TRASH IT.