SMTP tar pit feature for Microsoft Windows Server 2003

This article explains tar pitting your Windows 2003 Server.

Important This article contains information about how to modify the registry.

Click here for the full MS KB article (opens a new window).

What is SMTP tar pitting?

Tar pitting is the practice of deliberately inserting a delay into certain SMTP communications that are associated with spam or with other unwanted traffic. To be effective, these kinds of communications typically rely on generating a high volume of traffic. By slowing an SMTP conversation, you can dramatically reduce the rate at which automated spam can be sent or at which a dictionary attack can be conducted. Legitimate traffic may also be slowed by tar pitting.