Thunderbird - see what e-mail software people are using - useful for catching spam sometimes

I always find it interesting what people are using for e-mail clients. Sometimes I've noticed someone was using an older (exploitable) version of Outlook Express due to this setting and sent them a note that they should upgrade their software, as a safety precaution.

Anyway, if you set 'mailnews.headers.showUserAgent' to 'True' in the configuration editor, you will see the X-User-Agent: line displayed with each message you receive. You can sometimes filter mail based on this with known forged User-Agent strings, but most spam programs these days either don't set the user agent string or fudge them.