Rated 4 out of 5 stars

by dustypenguin13 on July 30, 2019 · permalink

If this extension is not working, you need to do this:

by Firefox user 8ccf9c on April 21, 2019 · permalink

**BINGO**

by Firefox user 0bef68 on Feb. 27, 2019 · permalink

There are numerous comments that the extension doesn't work with the latest version of Thunderbird. However, this fixes it:

Go to Thunderbird>>Tools>>Options>>Advanced>>General>>Config Editor

Scroll down to [email protected]

Right-click and select Reset

Repeat for [email protected]

Restart Thunderbird

Acknowledgements to arikurumo for finding this