Rated 5 out of 5 stars

Attention All Urgent Users that need this!!!!
I love the program and it works great, I work in IT for my family company. My Mum being older needed to have this program to use thunderbird at all.
After many many hours I stumbled across this:

"Instead of using TF&SC (currently for TB 60 and lower), try this: Edit/Preferences/Advanced/General/Config. editor, right-click the preference layout.css.devPixelsPerPx, Modify, and enter a value of 2.5 + That will zoom everything, including the global search tab text."

https://support.mozilla.org/en-US/questions/1269224

I hope this helps for everyone relying on this Add-On