Extending Thunderbird's wings
All the focus these days seems to be on Firefox extensions. Web Developer this, FlashGot that. But what about Mozilla Thunderbird? Here are five super extensions for the open source email client. (All were used on Thunderbird 184.108.40.206)
Thunderbird Header Tools enables you to change the header information on emails you've received.
The Remove Duplicate Messages extension, as the name suggests, removes duplicate messages from your mail folders.