This is NOT a responsive answer because it does not address my - and many others - issue: View in Browser in Outlook 365 (the program, not the web client). Every article I've seen about the retirement of IE and IE mode in Edge is all about "organizations that still need Internet Explorer 11 for backward compatibility with existing websites" (https://docs.microsoft.com/en-us/deployedge/edge-ie-mode). Outlook is NEVER mentioned.
Outlook is not a website; it is a program that Microsoft has published since 2000, if not older. This entire time, Outlook's "View in Browser" function has been serviced with IE up to Apriil updates. When I attempt to view a message in a browser now, I get the message in HTML or something that looks very much like it. There are no images and no live links. This is not a suitable replacement.
When - if ever - is Microsoft going to get off its butt and address this void in Outlook???