The new Outlook app will be packaged in an optional download for Windows 10 starting January 28th, but after the February 11th security update, it will be be a forced inclusion. T

You only have a few weeks before the new Outlook is forced onto your Windows 10 PC. The new Outlook will arrive automatically with an optional Windows 10 release that will ship on January 28, 2025. The app will then roll out to all Windows 10 PCs as part of the monthly security release to Windows 10 that will become available on February 11, 2025.

The good news is that the February update which brings the new Outlook doesn't strip out the old version of the app, so you can still use that.

Users of doomed operating system to receive unloved app via an update Microsoft's new Outlook will be automatically installed on Windows 10 machines as part of an upcoming monthly security release.… According to a message in the Microsoft 365 message center,

Microsoft will force install the new Outlook email client on Windows 10 systems starting with next month's security update.