Multiple features in Ipswitch IMail Server before 8.13 allow remote attackers to cause a denial of service (crash) via (1) a long sender field to the Queue Manager or (2) a long To field to the Web Messaging component.
https://exchange.xforce.ibmcloud.com/vulnerabilities/17222
https://exchange.xforce.ibmcloud.com/vulnerabilities/17219
http://www.securityfocus.com/bid/11106
http://support.ipswitch.com/kb/IM-20040902-DM01.htm#FIXES