The STARTTLS implementation in Kerio Connect 7.1.4 build 2985 and MailServer 6.x does not properly restrict I/O buffering, which allows man-in-the-middle attackers to insert commands into encrypted SMTP sessions by sending a cleartext command that is processed after TLS is in place, related to a "plaintext command injection" attack, a similar issue to CVE-2011-0411. NOTE: some of these details are obtained from third party information.
https://exchange.xforce.ibmcloud.com/vulnerabilities/65932
http://www.vupen.com/english/advisories/2011/0610
http://www.securityfocus.com/bid/46767
http://www.kb.cert.org/vuls/id/MAPG-8D9M4P