Betterbird doesn't hide its functionality behind paywalls, nor does it clutter your inbox with ads. It's fully open-source ...

Discover Betterbird, a refined fork of Thunderbird, offering enhanced features, stability and performance improvements for a ...

Nevermind, I figured it out. Apparently there were two different thunderbird directories and one was out of date. I ended up finding the right files in ./mozilla/Default\ User/Mail... not in the ...