From what I understood, SJU's name server occasionally goes berserk and issues authoritative statements about domains it normally has no authority to speak for, saying the host does not exist. This results in a permanent "no such host" failure which causes SMTP to bounce perfectly valid mail and report it as a permanent (550) error, which in turn causes users to be deleted from lists. If the incorrect information comes from SJU's name server, that's where the finger will point when people complain about lost mail. If you can't fix the name server, the next best thing is not to use it. Eric