Using classic Outlook for Windows in business environments
See this article for reverting back to legacy https://support.microsoft.com/en-us/topic/how-to-revert-to-an-earlier-version-of-office-2bd5c457-a917-d57e-35a1-f709e3dda841 Or see this article for customizing you outlook experience to your preference https://support.microsoft.com/en-us/office/change-the-look-and-feel-of-microsoft-365-63e65e1c-08d4-4dea-820e-335f54672310?ns=outlook&version=90&ui=en-us&rs=en-us&ad=us