Since 10/15/20 evening, I've been unable to send emails. I went through the processes suggested by Thunderbird and I called Comcast, my Internet provider. Everything is set up correctly on their end and they can see no reason for why emails aren't sending. They had me change the port # to see if that did anything. It didn't. I only get a small pop-up that says Sending of Message Failed. Every now and then a pop-up says unable to connect to SMTP server. It has no codes or anything else. Outgoing server name is smtp.Comcast.net. Port 465. SSL/TLS connection security. Authentication method normal. Username is full email address. Username@comcast.net. Comcast had me try two different Port #s with no effect. I tried to send another test email. This is the pop-up that finally came through: Connection to server imap.comcast.net timed out.