Tag the Bird 1.3 Requires Restart
by Paul Alexandrow
Tag the Bird gives the power of tagging to Thunderbird.
About this Add-on
Tags are stored directly into a message's headers, so they are fully search- and forwardable.
You can use http://tagthe.net to auto-tag your messages via a secure connection.
Suggestion of frequently used tags. Add them without touching the keyboard.
3 different ways of searching and organizing tagged mail.
You can define an arbitrary number of external search engines (like Google or del.icio.us) where you can search for your tags.