The remote host is vulnerable to a format string flaw.
The remote host is running a version of the Ipswitch Collaboration Suite / Ipswitch IMail IMAP server that is prone to a format string flaw. An attacker exploiting this flaw would send a malformed string to the remote mail server. Successful exploitation would result in the attacker executing arbitrary code. The affected SMTP arguments are: EXPN, MAIL, MAIL FROM, and RCPT TO. In addition, the remote host is vulnerable to a flaw when processing very long 'LIST' commands. Successful exploitation results in the remote service crashing.
Upgrade to version 8.22.0 of IMail or version 184.108.40.206 of the Ipswitch Collaboration Suite.