Thunderbird Error Message : Authentication Error : Unable To Log in at Server. TBird 150 will not install

We have no way of knowing if someone has "sabotaged" your computer. It's not likely, but possible, I guess. Not sure what you mean by "install". If you have been using Thunderbird for 10 years, is it not already installed? If you mean you're having trouble fetching or sending mail through Juno, the first thing to do is to confirm that you're using the correct server settings. I found this Juno page with their recommended settings. How do they compare with yours? https://help.juno.com/support/webmail/wm-email-setup.html Unfortunately, these instructions are incomplete. They don't mention some crucial settings, In order to manually set up a Thunderbird account, you need to know: - Whether it's an IMAP or POP3 account Incoming Server Type: IMAP or POP3 Incoming Server Name: Incoming Server Port: User Name: <usually your email address> Connection Security: SSL/TLS, STARTTLS, or other Authentication method: Normal password, OAuth2, or other SMTP Server Name: SMTP Port: Connection Security: SSL/TLS, STARTTLS, or other Authentication method: Normal password, OAuth2, or other User Name: <usually your email address> If you don't know the correct settings, and you can't find them online, you may have to contact Juno's tech support. Please do not create multiple threads for the same problem.