Challenge / Response

Challenge/Response systems are a somewhat foolproof way of dealing with SPAM. However, they have serious drawbacks of their own. At the very basic level, a C/R system sends a challenge email to the sender asking them to verify their identity. Once the sender has verified their identify, usually through a response to the challenge mail, the original email is delivered to the user. Unfortunately, this results in additional bandwidth usage and time delay. Users also run the risk of never receiving important emails sent by automated systems that can not respond to a challenge.

Open Source Solutions

Active Spam Killer
ASK is a Challenge/Response system.
Tagged Message Delivery Agent
TMDA is a Challenge/Response system with whitelite and blacklist support.

Page last modified on March 20, 2007, at 02:25 AM