Microsoft announced last year that it would be retiring the Windows Mail & Calendar apps in favor of the new Outlook at the end of 2024. As of January 1, these apps are no longer functional and will refuse to send or receive any more emails.

Designed to replace the current Mail and Calendar apps, the new Outlook can only be removed after it's been installed.

Microsoft 365 apps will only be available to use on Windows 11, as the company is ditching Windows 10 support for them.

For several months now, Microsoft has been urging Windows users to switch over to the new Outlook app, with classic Outlook recently getting an official “death date”. Many aren’t happy about this, holding off on jumping ship as long as they can — but the clock is ticking down.