Rated 5 out of 5 stars

Just what I wanted !

Talking about threads, do you know something which could join two threads, or split one thread in two ? (sometimes thunderbird don't sort really how I would want...)

This review is for a previous version of the add-on (0.4). 

There are some user prefs to change threading behavior and there is a longstanding bug for customizing threads (adding messages to a thread or splitting a thread). See bugzilla: