I suggest you check to see if you are using any addons, as that feature is working. You might also check by clicking help>troubleshoot mode and restart that way

Thank you for the suggestions, David.

I tried the troubleshoot mode, and all of my past emails still remained with white bodies and not with my original set color. I noticed that there is a "clear the startup cache" button and tried that. It didn't seem to help. However, I then went ahead and tried to compose a new email, and it had my selected body tint. I sent it to myself and the received email held that color.

I think that I can live with my past mail being a white eyesore as long as things look good going forward!

You are most welcome. :)