How to get started with Windows’ free ‘new Outlook’ app With the new Outlook, Microsoft is replacing the Calendar, Contacts, and Mail apps in Windows 10 and Windows 11 as well as in macOS.

The suggestion to "Try the new Outlook" in Windows Mail is the precursor to what will be a forced transition for Microsoft users sometime in 2024.

Microsoft is moving users of Windows 11’s Mail and Calendar apps to the new Outlook for Windows app. Existing users have until December 31st to move apps.