third message: I was able to get thunderbird to send emails with the settings previously noted. I closed the program. I re-opened thunderbird to send a new message and after the automatic update that so often happens, I tried to send a message and, even though my settings had not changed I got the error message about not supporting encrypted emails. I'm at wits end. I have set up microsoft mail but It doesn't have the added folders I have on my earthling addresses because those were set up in thunderbird and earthlink is a pop3 server. I could possible change over to imap if earthlink supports that now but I have no idea if I would still have that encrypted message error.

Hi Jeff, Could you try the solutions in the following TPG Community discussion, and see if any of them help: https://community.tpg.com.au/t5/Broadband-Internet/Unable-to-send-emails-error-Message-rejected-as-it-appears-to-be/td-p/90646

If you need help applying instructions, let us know.

Rosaliy, Jeff is the person who asked the original question, and this thread should be devoted to helping him with whatever problems he is having.

If you're having a issue, it would be best to use https://support.mozilla.org/en-US/questions/new/thunderbird/form where volunteers can get more details about your setup.

I solved this problem by resetting the password for my ISP. Thanks to the Mozilla community for the suggestions Regards Jeff