The image does not show the actual outgoing server smtp settings. Click on 'Edit SMTP server' button and then post image of it.

When you try to send what happens ? Do you get an error message, if yes, what does it say word for word ?

This was the "EDIT" button and it seems to be identical to the first window.

And when I just replied and sent a new message, they both went almost instantly and were sent....! Only thing that changed is that I had logged into my Xfinity account and accessed my email and successfully replied and sent emails from there. I guess Thunderbird just needed to be trained again for some reason.. Seems to be fine again...

Thanks for your effort...!

Forgot the .png file.....

Just for future reference, is that the EDIT button you meant?

Yes. Image is good. All the smtp server settings appear correct and you are using a secure connection.

It is possible comcast wanted you to logon to server webmail to confirm you are you before kick starting everything again.