Have you gone to the add on tab to see the status of your add on? Maybe it got disabled. Maybe it needs updating. Add Ons are from 3rd party software authors and it is up to them to keep current with the Thunderbird versions not to other way around. Just like it is up to you to make sure you upgrade them when needed.

There is no such thing as a Mozilla account so no idea what your talking about there.

You are free to use any email client you want.

First of all, there IS such a thing as a Mozilla account. I just logged in with one.

Secondly, I've already checked all of those things relative to the add-on I was using, including leaving a message for the developer of that add-on.

Now, it might be a wise enhancement for Mozilla to assure that menu fonts size can be changed without using a third party add-on, but it sounds like you're sure not interested.

As for me being free to use any free email client I want, I guess I'll just have to ignore all those requests for donations from Mozilla.

Too bad because I have donated in the past, and I have been a user of Thunderbird for over 10 years.

But that doesn't matter to you, does it? Thanks for the snappy response.

Thunderbird is not and has not for over a year or so been a Mozilla product. It has been taken over by a group of volunteers that make up the Thunderbird Council.

Your tone in your first post got an appropriate answer. Please do use another client. We have more than enough angry people.

https://support.mozilla.org/en-US/questions/1198299#answer-1060179

meaganmargaret said

First of all, there IS such a thing as a Mozilla account. I just logged in with one. Now, it might be a wise enhancement for Mozilla to...

An account on support.mozilla.org site is just an account on this site only as there is no universal Mozilla account for all *.mozilla.org sites that have accounts.

As for about Thunderboard not being a Mozilla product. ex: https://blog.mozilla.org/thunderbird/2017/05/thunderbirds-future-home/