Thunderbird e-mail downloading worked fine until morning of Friday, May 14. When I opened Thunderbird that morning, e-mails in the queue did not download. After a minute or two I received the following error message on the screen: "The RETR command did not succeed. Error retrieving message. Mail server pop3.frontier.com responded [SYS/TEMP] Server error-Please try again later" I clicked on OK and the message disappeared. Every time I have tried to download e-mail on Thunderbird since May 14 I receive the same message. It is now Sunday evening, May 16. I contacted Frontier tech support this morning. After checking the account settings, the tech support said that the inbound e-mail server address was correct and all other settings were correct. He suggested that I contact Thunderbird, hence this inquiry. I use Firefox 88.0.1 64 bit; Thunderbird 78.10.1 32 bit; Windows 10 Pro v. 20H2 Thanks for any help.