Rated 5 out of 5 stars
+ Works flawlessly
+ Opens on "recently used"
+ Open source (you're using Thunderbird...) and on GtiHub
+ Emoji are unicode with option to use system font ==> excellent cross-platform compatibility without increasing e-mail size
- Copies emoji to the clipboard instead of inserting directly, thus requiring an extra keystroke, BUT...
+ ...clipboard copy is actually really handy because Thunderbird is far from the only app with poor emoji support out-of-the-box 😄
+ Asks for NO PERMISSIONS AT ALL (might be _because_of_ clipboard copy)
TL;DR: what's not to like?!
I'm very happy to read this :D