Rated 5 out of 5 stars

It does work. Download it. Then go to tools>add ons and type in "manually sort folders"
Restart Thunderbird.
Go to tools and in the list you will find >Manually sort folders
Click on it and you can sort the folders.
Then restart.

Thank you very much. Love it.

This review is for a previous version of the add-on (2.0.2).