Microsoft plans to stop supporting Windows Mail, Calendar, and People apps later this year. The software giant has been moving existing users of these apps to the new Outlook for Windows app for the past few months, and now a set an end date for assistance for Mail, Calendar and People apps from December 31.

Once the apps reach the end of support later this year, Microsoft warns that users who haven’t moved to the new Outlook app “will no longer be able to send and receive email using Windows Mail and Calendar.”

Microsoft has been rolling out the new Outlook app for Windows for years now, and it has officially reached general availability in August. The new web-based Outlook is designed to eventually replace the full desktop version of Outlook as well, and Microsoft plans to give enterprise customers 12 months notice before it starts moving people away from the desktop version of Outlook.

Existing installations of classic Outlook through perpetual and subscription licenses will continue to be supported until at least 2029, so it will take some time for Microsoft to fully migrate all Outlook users to this new application. It starts with the Windows Mail and Calendar apps later this year, followed by a phase-out for Outlook on Windows. You can read more about Microsoft’s timeline for the new Outlook for Windows here.