I saw that a couple of times tonight on Beta, but after restarting a few times it hasn't happened again.

Edit: I'm using Fastmail and just learned there was a problem with it earlier, which likely caused my problem. Are you using Fastmail?

I'm not using any variation or other access source. Just pure Thunderbird.'\

I've received this message off and on for over 6 months. Earlier it would not go away and caused problems. I tried every alternative short of reinstalling. Finally, I reinstalled it on both of my PC's and it went away for a long time, but just in the last two weeks it returned on both. Naturally, I reinstalled again as the solution, but this time it came back.

As you said, after several times it quit. But it is an aggravation.

Thanks for reply.

I'm not using any variation or other access source. Just pure Thunderbird.'\ But you are connecting to your email provider via TB. Who is your your email provider?

Not sure what you are asking. Internet provider is Spectrum. Email provider is GMAIL of course.