Ipswitch Imail 6.0 allows remote attackers to cause a denial of service via a large number of connections in which a long Host: header is sent, which causes a thread to crash.

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.