Office 365 Mac OS High Sierra Users: Legacy Authentication Update

As of October 1, users who have not updated their Office 365 accounts to use modern authentication will no longer be able to log in on their devices running Mac OS High Sierra. This means that many users may need to remove and re-add their email profile to their device.

For those who have already updated some of their devices but are still receiving notifications about legacy authentication, it is recommended to update all of your devices. Unfortunately, Microsoft does not provide detailed information on which devices are using legacy authentication.

If you receive a notification that your account has been seen using legacy authentication, you will need to update one or more of your devices. To determine if you are affected by this change, you can expect communications from Microsoft beginning April 11, 2022.

In addition to updating their device settings, some users may also need to update their Office software or email client, or switch to accessing Exchange email via Outlook on the Web. Others may only need to remove and re-add their email profile from their device.

It's worth noting that even up-to-date applications can be configured to use legacy authentication, so this may affect certain applications as well. Microsoft disabled legacy authentication for OSU starting October 1, 2022 at around 2:15pm.

From this date forward, any applications using legacy authentication will lose access to OSU email, calendar, or Office 365 services. This change will impact how Microsoft applications are able to sync OSU email, calendar, and other Office 365 tools.

Finally, it's important to note that Microsoft will end support for legacy authentication as of October 1, 2022. With this update, Office 365 Mac OS High Sierra users can expect a smoother and more secure experience with their accounts.

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Office 365 macos high sierra