Jessica_Wilczekthank you for the reply all message above, but I would point out that the feedback mechanism for switching back isn't ideal when the product limitations prevent me from even trying the new interface in the first place.
I have all of my mail in folders "on my computer" and an extensive set of rules to manage emails into folders. So I can't even try the new interface since it would wipe out everything I have in Outlook currently.
So, tying the feedback mechanism to the toggle switch doesn't really help you gain visibility to users who are prevented from trying the new interface at all.
My feedback is that I would be open to moving all of my mail to the server side inbox, if all of my folders and rules could be automatically migrated as well. And I would need some mechanism for managing emails if I am over my storage quota on the server (that's why I have my emails on my computer in the first place.)