“Microsoft is building a universal Outlook client for Windows and Mac that will also replace the default Mail & Calendar apps on Windows 10 when ready. This new client is codenamed Monarch and is based on the already available Outlook Web app available in a browser today.“
“Project Monarch is the end-goal for Microsoft’s “One Outlook” vision, which aims to build a single Outlook client that works across PC, Mac, and the Web. Right now, Microsoft has a number of different Outlook clients for desktop, including Outlook Web, Outlook (Win32) for Windows, Outlook for Mac, and Mail & Calendar on Windows 10.“
Microsoft is building a new Outlook app for Windows and Mac powered by the web | Windows Central