The NAD (which I believe is only the POSTMASTer account
at your site) and LISTSERV maintainer can issue
 
QUIET DEL * userid@node
 
in the first case.  In the second case, append (NETWIDE.  Or, if
the userid no longer exists, a current version of your MAILER
will do the informing of other LISTSERV lists as they generate
mail to the non-existent account.
 
/Pete Weiss