ITS FIXED! Yahoo! :) v16.19
Having felt the annoyance of this for the past few weeks I just updated expecting this to be fix and..... no :(
Permanent toggle switch PLEASE!
Thanks for the feedback! We are working on this.
Current Dark Mode support: https://docs.microsoft.com/en-us/officeupdates/release-notes-office-for-mac
Just updated to 16.28 and still no toggle to permanently keep the message background light.... Aghhhhh! 😭