Rated 5 out of 5 stars

For use with TB 3.1:
- download the xpi file, rename it to .zip
- open the included install.rdf with editor
- in <em:targetApplication> <!-- Thunderbird --> change the value for <em:maxversion> to 3.1
- save the changed zip file and rename back to .xpi
- Install

This worked for me.

By the way: gread addon! It makes our work a lot easier!

Regards
Sebastian

This review is for a previous version of the add-on (0.9.10.1).