Rated 4 out of 5 stars

Want to give it five, but need to stop four really want to give a 4.9. Here's why.
If I start an email thread with my brother w/subject "whats up?", then weeks later someone sends me an email w subject "whats up?" they get grouped in same thread, even though the two senders were never sending/recieving the same email string. Aside from that, perfect

This review is for a previous version of the add-on (0.6). 

Thanks for the review. The problem you're describing is actually a problem with Thunderbird. All this extension is doing is asking Thunderbird to resort the emails - it doesn't actually do any of the sorting itself.