The POP3 Server in ArGoSoft Mail Server Pro 1.8 allows remote attackers to obtain sensitive information via the _DUMP command, which reveals the operating system, registered user, and registration code.
http://www.vupen.com/english/advisories/2006/0733
http://www.securityfocus.com/bid/16808
http://www.securityfocus.com/archive/1/425968/100/0/threaded