The STARTTLS implementation in the server in Ipswitch IMail 11.03 and earlier 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.
http://secunia.com/advisories/43676
http://www.kb.cert.org/vuls/id/555316
http://www.kb.cert.org/vuls/id/MAPG-8DBRD4
http://www.securityfocus.com/bid/46767