The only changes I made to Thunderbird was the mail.mediacombb.com server name. Otherwise, it's presently working with the old settings, as is my Mac mail. I can only hope it stays up!
Thanks Jason, and everybody else on this forum.
I'm keeping this page open and bookmarked to monitor progress.
I've used Hotmail more in the past 2 weeks more than I have in the 12 years that I've had that address!