As far as I know, the iOS and iPadOS Mail apps are fine and do not use EWS anymore. The Mail app on macOS does rely on EWS for some parts and would no longer work with EWS disabled.
Yesterday I applied Microsofts Baseline security mode on my Microsoft 365 subscription. This blocks EWS ahead of the global disabling of this on Exchange Online as of October 2026. As expected, the Exchange account within the Mail app on macOS stopped working. The Mail app on iOS is still working fine.
As you would expect, Microsoft and Apple are aware of this. I received a message this morning in the M365 admin centre.
...
How this affects your organization:
In October 2026 we will begin disabling EWS on all M365 tenants worldwide. EWS Applications that have not been migrated will stop functioning.
The following applications on your tenant use EWS:
Entra Application ID
Apple Mail for Mac (f8d98a96-0999-43f5-8af3-69971c7bb423)
...
Note on Apple Mail for Mac
Apple Mail for Mac and related applications are some of the most popular EWS applications. We are working closely with Apple to update these applications. In order to run your tenant in the most secure configuration today, users of Apple Mail for Mac would have to switch to an alternative like Outlook for Mac until the applications have been updated.
Still surprising that this has not been solved already, but hopefully Apple will fix this before October 2026. 🤞
I am leaving EWS disabled for now and will use Outlook for Mac until this is fixed.
