Because of the viral way McAfee inject their extension into a running Thunderbird you have to disable it in McAfee itself.

Even after I shut off the McAfee email, it is still visible in the Thunderbird and it was still putting emails in Spam. Thunderbird allowed me to install the extension. I am so sorry that I cannot disable the extension. Unless you can help me do a clean install of the Thunderbird, I will no be able to use the program. Very sad.

This post suggests McAfee installs files in the TB Program Files folder, so even after uninstalling TB, they may remain. So, when you uninstall TB from Windows Settings, delete the TB folder in Programs Files to remove any leftover McAfee files.

It might also be they have learned a valuable leason and you can just disable their add-on in the add-on manger in Thunderbird.

Basically your asking the wrong people, we do not use McAfee and don't want to. So we are not rally a good choice to ask how to use it. McAfee have a support service, use it to ask them how ti disable their stuff. Previous posts indicate they will even remote into your system and configure it for you. We certainly will not.

When I had Thunderbird installed, I looked for the add-on manager. Can you tell me what menu to look under. I want to reinstall Thunderbird and quickly disable the add-on before it messes up my emails again. I could not find it. This may sound like a stupid question. I am sorry. You should be capable of telling me where to locate that menu.

There are 2 ways to get to Add Ons. Both are pretty obvious if you look at the menu choices.

If using the Menu bar it is under Tools-Add Ons. If your Menu bar is hidden press the alt key to may it show.

If using the AppMenu button, the 3 horizontal line button, click that button and Add Ons is in the main menu.

See image if you need help finding these choices.