A major annoyance in instant messaging is the amount of spam prevalent in the Yahoo and MSN networks these days. Largely because of the “email as contact name” paradigm, these contact addresses are easily scrapped from websites. We don’t like it any more than you do.

In an attempt to combat this, I’ve created a plugin called Challenge/Response. It works by hiding messages from unknown users until the user answers a question you have picked. For example, you can set your message as, “What is the square root of 49 in numerical form?” Until the unknown user answers “7” all of their messages are hidden from you. 

Unknown users are those not on your contact list, not in the C/R white-list, and those you do not have a chat window open for. If set to do so, C/R will log the messages you receive to a group chat. It can also hide messages from all blocked users, for protocols like MSN where blocking only hides status information.

Since spam bots can’t read the challenge, it’s unlikely for them to respond and get past the filtering system. The downside is that people who want to talk to you for the first time may be confused or unable to answer; by making your challenge and response easier, you can avoid this problem.

Challenge/Response isn’t being included as part of Adium because it’s more of a band-aid than an actual solution, and because presenting it as a third-party plugin allows it a few luxuries that being a core part of Adium wouldn’t allow it. Eventually I’d like to see some sort of intelligent filter which is able to tell the difference between spam and non-spam messages, possibly with something like a Bayesian filter used by e-mail clients.

If you run into any bugs, or have any suggestions, feel free to make a comment here or on the Xtras page for the plugin. Since we don’t have an in-app way of updating plugins yet, check back on the site every once in a while to make sure you’re using the latest version. Enjoy. 😉