login.aspx in SmarterTools SmarterMail 1.6.1511 and 1.6.1529 allows remote attackers to cause a denial of service via a long txtusername parameter, possibly due to a buffer overflow.
https://exchange.xforce.ibmcloud.com/vulnerabilities/15390
https://euvd.enisa.europa.eu/vulnerability/EUVD-2004-2578
http://www.zone-h.org/advisories/read/id=4098
http://secunia.com/advisories/11042
http://members.lycos.co.uk/r34ct/main/smarter_mail%203.1/smarter_mail.txt