Floositek FTGate PRO 1.05 allows remote attackers to cause a denial of service (memory and CPU consumption) via a large number of RCPT TO: messages during an SMTP session.
http://www.securityfocus.com/bid/4428
http://www.security.nnov.ru/advisories/ftgate.asp
http://www.iss.net/security_center/static/8750.php
http://www.ftgate.com/knwldgbs/hotfix.htm
http://archives.neohapsis.com/archives/bugtraq/2002-04/0053.html