You could try setting list headers to SUBSCRIBE=Owner,Confirm.  That will
at least give you an opportunity to screen any hotmail.com subscribers. And
if, as your message suggests, he is using his personal name at all times
(Otherwise, how could you identify him?) that would be a way of screening
him.

A more drastic method would be to filter out all future hotmail.com
subsription requests.

--
Dr. W. Schipper                     Email: [log in to unmask]
Department of English,              Tel: 709-737-4406
Memorial University                 Fax: 709-737-4528
St John's, Nfld. A1C 5S7