Guardian Digital has issued updated packages for Postfix. These fix two vulnerabilities, which can be exploited by malicious people to cause a DoS (Denial of Service) on a vulnerable system or use it to conduct bounce scans and Distributed DoS attacks against other systems.

For more information:
http://secunia.com/advisories/9433/

Solution
The updated packages are available via Guardian Digital Secure Network.
Original Advisory
http://www.linuxsecurity.com/advisories/engarde_advisory-3517.html

Deep Links
Links available to Secunia VIM customers