Unspecified vulnerability in the POP service in Stalker CommuniGate Pro 5.1c1 and earlier allows remote attackers to cause a denial of service (server crash) via unspecified vectors involving opening an empty inbox.
https://exchange.xforce.ibmcloud.com/vulnerabilities/27500
http://www.vupen.com/english/advisories/2006/2632
http://www.securityfocus.com/bid/18770