It seems that the new Outlook app for desktop doesn't allow background images/themes, a feature present in the default windows app. Is there some workaround, alternative, or plugin I could be using that is just as fast, has the same features/functionality, and the same level of integration with my 365 account. Having a silly background image really helps break up the monotony of the day, picture included below comparing the default Windows Mail app on the left and Outlook 365 on the right.
