Rated 4 out of 5 stars

Works as advertised, thank you! However, the permissions asked are frightening (full access to Thunderbird and to the computer). As Comunica2 mentioned, one can disable the plugin when not used as a workaround.

This review is for a previous version of the add-on (2.1.1). 

I think many other add-ons are the same.
Add-ons published on addons.thunderbird.net (ATN) have passed human review.
In addition, the source code of this add-on is open, and anyone can check it.