Rated 3 out of 5 stars

To install do the following steps.
1. Unzip the files on the downloaded file.
2. edit file "install.rdf" in a text editor
3. search for "Thunderbird" comment line.
4. Just below comment line find "maxversion" line. I changed it to version "52.5.*". (My current version is v52.5.0 on linux.)
5. Then zip all the files to the same name it was previously.
6. Install addon. It worked for me.

This review is for a previous version of the add-on (20110323.1-typefix).