Apple Mail on the Mac may stop syncing properly with Microsoft 365 accounts as Microsoft begins retiring Exchange Web Services, or EWS, from Exchange Online. MacRumors and tbreak both covered the issue this week, and my first reaction was pretty simple: if your organization runs Microsoft 365, why are you still using Apple Mail?

Microsoft has been warning about the end of EWS for years. The current retirement process is now underway, with full disablement scheduled for April 1, 2027. Microsoft laid out the timeline in Exchange Online EWS, your time is almost up, and later introduced EWSAllowedAppIDs so admins can temporarily allow specific applications while they migrate away from EWS.

Apple is working with Microsoft to move Mail, Calendar, Contacts, Notes and Reminders to Microsoft Graph in a future macOS update, so this is not some permanent incompatibility between Apple and Microsoft. The problem is timing. Microsoft is retiring the old plumbing now, while Apple is still replacing it.

And this is where I struggle to understand the appeal of sticking with Apple Mail for a Microsoft 365 work account. Outlook for Mac is already built for Exchange Online and Microsoft 365. It supports the platform directly, without adding another dependency that your admin may have to babysit during a protocol retirement. If you have not looked at it recently, Microsoft has the current Outlook for Mac experience available now.

I am not saying Outlook for Mac is perfect because it’s not. But if your organization already lives in Microsoft 365, using the Microsoft client for Microsoft email seems like the path with fewer moving parts. Apple Mail might feel simpler because it is native to macOS, but once your company mailbox depends on a compatibility layer that is being retired, that simplicity gets a little questionable.

For admins, the answer is the same as with every EWS dependency: identify what is still using it, decide what genuinely needs a temporary exception, and get rid of the dependency before April 1, 2027. For a legacy business application, that might require real migration work. For somebody reading their Microsoft 365 email on a Mac, I would start with a much simpler question.

Why are you not just using Outlook for Mac?

I am genuinely curious. Is it the interface, performance, unified inbox, habit, or something Outlook still does badly enough that you would rather stay on Apple Mail? Tell me, because this is one of those cases where I want to understand what I am missing.