Rated 1 out of 5 stars

Installed manual sort add on. Now what? Nothing happens, nor can I find any instructions how to use. Ridiculous that this function is not standard in the email app.

This review is for a previous version of the add-on (2.2.1). 

Have you read "About this Add-on"? Did you still not know where and what is added by this add-on? Or did you launch the added menu item and not know how to use it?
Also, wouldn't it be out of line to use your rating for the email app as a grade for this add-on?
Thunderbird is also evolving, albeit slowly. Until recent versions, it was not possible to sort accounts, but now it is (so there is not much need now to use this add-on for sorting accounts). But unfortunately, there is still no ability to sort folders, so this add-on is still on.