To try the thousands of add-ons available here, download Mozilla Firefox, a fast, free way to surf the Web!
CloseWelcome to Firefox Add-ons.
Choose from thousands of extra features and styles to make Firefox your own.
CloseReview for Remove Duplicate Messages by akahige
Rated 1 out of 5 stars
Abandoned and does not work with Thunderbird 3.
Use Remove Duplicate Messages (Alternate) : https://addons.mozilla.org/en-US/thunderbird/addon/4654
It's a five star replacement.
To create your own collections, you must have a Mozilla Add-ons account.