Rated 5 out of 5 stars

This is very good extension. Has many options for good matching. I used it very long time. My only problem is that our mail server often sends one email several times when the recipient is included in more then one alias. Unfortunately it is not possible the extension to be created in a way do this automatically on new email receiving.

But I found there is a config property mail.server.default.dup_action that can do this.
http://www.ghacks.net/2007/05/18/automatically-remove-duplicate-mails-in-thunderbird/

Thanks for the extension I still use it when I need to compare many emails.

This review is for a previous version of the add-on (0.3.2).