That is generally a network problem, not an email account problem. What you might try is going to config editor at settings>general and set mailnews.tcptimeout to 300. The default is 100, and increasing to 300 may address your issue.

Thanks, David, but I couldn't find config editor or mailnews.tcptimeout anywhere on my ISP Spectrum program or Thunderbird. Where exactly do I find it?

In Thunderbird, click settings>general - or possibly Tools>settings>general and scroll to bottom to the config editor.

I found I just didn't scroll down far enough there. I made the change you suggested but still no change. Do I need to reboot to make that change take effect?

If it works, it should work after restarting Thunderbird. I've seen it work fine for downloading, but unsure of outgoing.

David, I rebooted after making the change and I still can't send out mail. Any other ideas? Jerry

timeouts have no easy solution. It may be as simple as rebooting your router. You might also recheck your SMTP server setup to ensure it's correctly set. Or increase the setting on the timeout to 500.

Thanks again, David. I'll try those. I really don't want to quit Thunderbird. Jerry

Well, you have to do what you have to do. To me, Thunderbird is just a messenger. People blame it when they forget their passwords, when they have specified incorrect settings, when they provide the wrong password, and much more. And it's always possible that Thunderbird is doing something wrong, but that is rare. A timeout comes from the internet. If all is failing and you are dependent on your emails, then you may want to try elsewhere. Do let me know if any other approach works.

I'm getting to that point, David, but I will fiddle with it a bit more. I've used Thunderbird for years and am quite used to using it. It's a good service and I send a monthly donation. Jerry

Thank you. We get many posts about Spectrum and, apparently, the settings are not consistent across all the domains they serve, so there may be a benefit in experimenting with your settings.

Sudden stoppages of sending and timeouts can often be caused by an antivirus that becomes incompatible with TB. State your AV app, and try running Windows in safe mode to test the effect of startup apps like AV (which are bypassed in Windows safe mode).

Not sure what you mean by "State your AV app...". I'll try Windows in safe mode.

What is your antivirus, especially if it's not Windows Security?

I use PC Matic.

Post the results of running Windows in safe mode, and exclude the TB profile folder from PC Matic, as well as excluding it from scanning secure connections, and disable the VPN if you have one.

I ran windows in safe mode and received the same message about the smpt outgoing server settings. I do not have a VPN operating. I could not find how to exclude the TB profile folder from PC Matic. Thanks again for your help but this just looks hopeless. Jerry

What exactly are your smtp settings? The specific server depends on your account domain, but the other settings are: port 587, connection security = STARTTLS, authentication = normal password, and User Name = email address.

https://www.spectrum.net/support/internet/mobile-email-setup

Thanks. Went through that over and over after getting the settings from Spectrum. My initial check of those settings showed they were correct. The smtp just quit working overnight with no activity in the system on my part. I guess it is bye-bye to Thunderbird.

Did you try disabling PC-Matic to see if that made a difference?