Rated 5 out of 5 stars

by troglobyte on April 7, 2017 ·

Silvermel current version (v2.0.1) isn't compatible with Thunderbird 52.*
You can edit the extension to use it in v52 and looks like Silvermel works fine.
Instructions: http://forums.mozillazine.org/viewtopic.php?f=48&t=1520265&sid=31621ec02c683ac9d464d5b1e9f26774&start=1755

This user has a previous review of this add-on.