The remote host is missing an update to the system as announced in the referenced advisory.

Update your system with the appropriate patches or software upgrades. http://www.postfix.org/CVE-2011-0411.html http://secunia.com/advisories/43646/ http://www.vuxml.org/freebsd/14a6f516-502f-11e0-b448-bbfa2731f9c7.html

The following packages are affected: postfix postfix-base postfix-current postfix-current-base CVE-2011-0411 The STARTTLS implementation in Postfix 2.4.x before 2.4.16, 2.5.x before 2.5.12, 2.6.x before 2.6.9, and 2.7.x before 2.7.3 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.