The SMTP service in MailEnable Enterprise 1.04 and earlier and Professional 1.54 and earlier allows remote attackers to cause a denial of service (server crash) via an EHLO command with a Unicode string.
https://exchange.xforce.ibmcloud.com/vulnerabilities/19973
https://exchange.xforce.ibmcloud.com/vulnerabilities/19948
http://www.mailenable.com/hotfix/
http://securitytracker.com/id?1013637