This could be due to a corrupted/broken e-mail in your inbox on the e-mail server.

1. Quit Thunderbird. 2. Use your web browser to log into your webmail. 3. Open the first/oldest message in your inbox. Read it, then either delete it or move it to another folder. 4. Wait a minute, then open Thunderbird and see if it will get your new messages now. 5. If it doesn't, then go back your webmail and do the same to the next oldest message.

Thanks for the suggestion. But, I tried it, and am still getting the same error message.

Look at this thread: https://support.mozilla.org/en-US/questions/1007299

It is your exact situation, also with RoadRunner. Try the solution there.

The procedure suggested in the linked thread, did the trick. It didn't at first, as the popdat I was supposed to delete kept reappearing as soon as I restarted Thunderbird. However, once I closed everything, and rebooted the computer, then started things back up, it finally worked.

Thanks for the help. Much appreciated.

While that works, I am starting to think this may be related to server names. Of late there has been a spate of road runner folk with a collection of almost random looking errors, but I am thinking it may be that they are still using the old road runner server names instead of the time warner ones that have replaced them.

The current settings for road runner are here https://www.timewarnercable.com/en/support/faqs/faqs-internet/e-mailacco/incoming-outgoing-server-addresses.html

That the error contains a message about Mail server Pop-server.roadrunner.com indicates you are not using those settings.

@Bruce, you have be more here than I in recent weeks. what is your opinion?

I agree that Time Warner / Road Runner customers are having lots of problems in the past week. I don't know enough to know if the e-mail servers and their settings have changed recently.

"The RETR command did not succeed" error messages have become a cringe-worthy issue for me.

I do not think the settings have changed recently... I do think past changes and the transition periods for them may be coming to a close. The RETR errors may well be a sign that TWC have finally migrated mail from the old road runner infrastructure to their own, hence the obsolescence of the message id's stored in Thunderbird.