Secunia Security Advisory – Debian has issued an update for courier. This fixes a vulnerability, which potentially can be exploited by malicious people to cause a DoS (Denial of Service).
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/39609/sa16561.txt
Source: https://packetstormsecurity.com/files/39609/Secunia-Security-Advisory-16561.html