My guess is it is neither godaddy nor Thunderbird.

What anti virus do you use? Does disabling it's email scanner help?

I have Norton Internet Security. I disabled the email scanner and rebooted, then attempted to open Thunderbird. I received a barrage of popups that claimed login to the mail server failed, with three buttons, Retry, Enter New Password, and Cancel. After pressing the Retry button several times the popup goes away, but I am still not connected to the server.

We have been having the same errors in my office, 30 computers or so. The few with outlook work fine.

I believe a workaround is to edit the settings for each account in thunderbird and disable SSL for the incoming and outgoing server settings.

I tried that a little while ago on a few computers and it seems to be working, however I do not like having zero security. Would be nice if Mozilla addressed this issue. (Or if godaddy updated their servers to be more future compatible). Whichever it is.

I have found in the past that disabling SSL breaks things, so don't want to go there. Godaddy insists the problem is not on their end.

My wife's computer is set up the same as mine (I built, maintain and configured both machines), however she is not having the same issues with Thunderbird. She is also using Outlook and no problems there.

The strange thing is that I wasn't having any problems either until the last couple of days, and I didn't make any recent changes to my Thunderbird or security software.

I hate this, I just need my email to work!

I am getting the same problem!

OK, lets come at this the old fashioned way. My guess is it is the Norton Firewall, they are getting heavily into white listing applications and it manifest itself as not working mail applications every time there is an update. So check that for allowing Thunderbird full access to the internet. May particular notice of the version. Norton's appears to think 38.5.0 is not close enough to 38.5.1 to allow it to continue to run. only 38.5.0 is white listed.

The following procedure will remove third party programs and should also bypass the firewall component as it should not be loaded.

Restart the operating system in safe mode with Networking. This loads only the very basics needed to start your computer while enabling an Internet connection. Click on your operating system for instructions on how to start in safe mode: Windows 8, Windows 7, Windows Vista, Windows XP, OSX

This is an example of Norton's white listing and firewall rules. Even though the original poster does not know it. https://support.mozilla.org/en-US/questions/1104205?utm_campaign=questions-reply&utm_medium=email&utm_source=notification

Norton firewall appears to allow all traffic from/to Thunderbird, regardless of the version. Please see attached screen shot of the Norton config for Thunderbird/.

We do not use Norton in our office, we use AVG and / or Malwarebytes. I have checked several computers and neither one has updated recently nor are their firewall settings active.

How is it Mozilla updates thunderbird to use SHA-2 and immediately after it stops working with Godaddy using SSL encryption. Either Godaddy is still using SHA-1 and Mozilla didn't make the update backwards compatible, or One of the two implemented SHA-2 poorly (probably godaddy). Maybe godaddy has a seperate port / server for SHA-2 Connections.