I have two successful emails running in Thunderbird Email, on my MacBook Pro, macOS Tahoe 26.3.1; however, a third one fails to get registered. The error message says unable to access server, " which may be due to username or password. I have checked several times to make sure I am entering the correct email and password. Still no luck, and my email service provider, "Rogers Together With Shaw," says that everything is on their side, is correct, as I can access my Webmail they have, which they assure me goes via the Internet, like any other email app out there, meaning the problem resides with Mozilla Thunderbird. Ask them. I am now asking. Looking forward to a meaningful reply.