A few weeks ago I started noticing the following error notification every time Thunderbird checks for email or I send an email: "Server mail.server.com has disconnected. The server may have gone down or there might be a network problem." The "mail.server.com" in question is my OLD mail server. I migrated to a different one a year ago. It's now defunct. I went through my settings and all incoming servers are set to the new server, as are all my SMTP server settings. I can't find anywhere in my settings that could be hanging on to the old server hostname. And my mail seems to work. I can send mail, receive mail, or at least I'm unaware if I'm not receiving any. Spam certainly gets through. And these notifications only started up very recently. The mail server changes were made a year ago. Any idea what's going on? I'm currently running Thunderbird 78.8.1 (64-bit) on a Ubuntu 20.04.1 LTS system. Thank you.