I also tried this: How to enable outdated security protocols TLS 1.0 and 1.1 Open Config Editor (about:config) ≡ > Options > Find in Options In the searchbox, type: about:config, then press Enter. Click on the button Config Editor… in the search result. In the about:config dialog, search for: security.tls.version.min Double-click on the found preference security.tls.version.min and change its value to 1, then press Enter. Restart Thunderbird and try to download your messages. If you can receive and/or send your messages after changing this preference:

Please inform your email provider to upgrade the security protocols on the server to support TLS 1.2. Revert the preference security.tls.version.min to its original value as soon as possible by repeating the above procedure, then right-click on the preference and choose Reset from the context menu.

https://support.mozilla.org/kb/cannot-receive-messages

Tried this, did not work:

How to enable outdated security protocols TLS 1.0 and 1.1 Open Config Editor (about:config) ≡ > Options > Find in Options In the searchbox, type: about:config, then press Enter. Click on the button Config Editor… in the search result. In the about:config dialog, search for: security.tls.version.min Double-click on the found preference security.tls.version.min and change its value to 1, then press Enter. Restart Thunderbird and try to download your messages. If you can receive and/or send your messages after changing this preference:

Please inform your email provider to upgrade the security protocols on the server to support TLS 1.2. Revert the preference security.tls.version.min to its original value as soon as possible by repeating the above procedure, then right-click on the preference and choose Reset from the context menu.

For some reason, the mail finally transferred from my Windstream account to Thunderbird....do not understand why?

Back again with same problem. I even reverted back to Thunderbird 78.8.0 and no luck.

When I ask to get messages for my Windstream account, Thunderbird says it is downloading 1 of 47, but nothing comes in.

Really stumped as to what is going on.

Any help greatly appreciated.

What is your anti-virus software?

I use Windows Defender, Malwarebytes, and a VPN. It's working today. I checked jy wife's Thunderbird profile and mine was just like hers. Must be something with my PC. It's not 78.10.0 as that is the version my wife is using. Close this ticket as I have no idea what is the cause for not receiving emails from my Windstream.net account.

It's working today.

Likely the problem will occur again. Chances are the culprit is anti-virus software. To rule out problems with anti-virus software try to start Windows 10 in safe mode with networking enabled.

Please report back your results.