Excellent! Rated 5 out of 5 stars

This extension is what I was looking for, it brings Thunderbird to a new level! Many thanks to the developers and keep up with the good work.
Just a suggestion: the actual Reply/Reply all/Forward buttons should appear as a single "Reply" popup button (where you may choose the reply/reply all/forward action) not below the message body but just to the right of each message title (if you want to reply to a given message) and also on top of the coversation (to reply to the most recent message).
See how Postbox handles this, it's just what I mean:
http://static.postbox-inc.com/img/screenshots/large/pb2-convo.png

This review is for a previous version of the add-on (2.0alpha2).