Go to your email providers webmail page and delete or move the message that keeps downloading. See if that lets the remaining messages download.

The lock on the account folder means the same thing as the lock at the beginning of the url for this webpage. It is secure. It is amazing how many people first notice this lock when they have an issue. When did it appear? When you added this account to Thunderbird with secure settings required by your email provider.

Thanks for your response.

I went to email provider (Cox.net) and looked over the three messages there, but the one that keeps downloading was not there. So what now?

look in the spam folder of cox web site mail.

Is your anti virus AVG? https://wiki.mozilla.org/Thunderbird:Testing:Antivirus_Related_Performance_Issues#AVG

Thanks Matt.

I use the paid version of AVG. I have not had any problems with it in the past several years that I have used it.

The location of the option is in settings/components/mail shield/main settings/scan inbound mail. I turned of the scan of the inbound mail and opened Thunderbird and immediately received about 86 messages that I could not get before.

I know it is dangerous to turn off the scan, but this was the only way to get the messages.

There are several things that I want to read about in the AVG forum about this problem.

Thanks again Matt.