In recent months, the company has been migrating existing users of these applications to the new Outlook app for Windows, and now it has announced the end-of-support date for the "Mail," "Calendar," and "People" apps — December 31.
After support for these programs ends at the end of this year, Microsoft warns that users who have not transitioned to the new version of Outlook "will no longer be able to send and receive emails using Windows 'Mail' and 'Calendar'."