Apple Mail (macos) does not work with MS Hosted Exchange

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Level 1

25 points

Apple Mail (macos) does not work with MS Hosted Exchange

I am using an MS Hosted Exchange email. I was able to setup this account without any issues on my iPad and iPhone (iOS 26).

Now I am setting up a new MacBook Pro 16 2024 and Apple Mail is refusing to connect to the MS Hosted Exchange server. It is throwing this error message:

I found this thread on MS ignite that seems to describe the issue. It seems that Apple Mail is trying to connect to MS Hosted Exchange using basic authentication, which is not accepted by MS Hosted Exchange any more. Can anyone enlighten me how I can force Apple Mail to use modern authentication. The Apple Mail clients on iPhone and iPad seem to use modern authentication by default.

MacBook Pro (M4 Pro, 2024)

Posted on Oct 26, 2025 3:06 AM

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Answer 1

AlWeir

Level 5

4,880 points

Oct 26, 2025 6:43 AM in response to jacobacci

Re-adding the Account: Delete the Exchange account from System Settings > Internet Accounts and add it again, ensuring you select the Microsoft Exchange option during setup.

Using a Manual Configuration: In some macOS versions, manually configuring the server settings (often using outlook.office365.com for hosted Exchange) can bypass automatic setup issues.

Clearing Keychain Entries: Remove any related Exchange or Office 365 passwords and tokens from the Keychain Access utility before re-adding the account.

The Keychain.app is located in the Utilities Folder on the Mac. If you are using the Passwords.app remove the entries in there as well.

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Answer 2

Oct 26, 2025 6:45 AM in response to AlWeir

AlWeir wrote:

…The Keychain.app is located in the Utilities Folder on the Mac. If you are using the Passwords.app remove the entries in there as well.

The older Keychain Access app and the new Passwords app are two paths into the same password-related info.

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Answer 3

AlWeir

Level 5

4,880 points

Oct 27, 2025 5:33 AM in response to jacobacci

You could use the Outlook.app that is on the App Store for the time being until you figure out what Mail is doing wrong.

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Answer 4

jacobacci Author

Level 1

25 points

Oct 27, 2025 12:49 AM in response to AlWeir

Thanks, I have tried removing and re-adding the account several times to no avail.

In the meantime I have diagnosed the following:

Adding my xxxxx@outlook.com account (as Microsoft Exchange) works fine. A browser windows with the oauth2 login opens immediately and after completion of the process, the account works
The same is true for a Gmail account, which also uses oauth2 via a browser window
If I try to add my Hostes Exchange account, no oauth2 browser windows opens. It looks like Apple Mail tries to access the account using basic authentication instead of using modern authentication. Somehow Apple Mail and the Hosted Exchange server don't seem to see eye to eye about how to authenticate

I would welcome any hints how to solve this short of using Outlook

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Answer 5

AlWeir

Level 5

4,880 points

Oct 26, 2025 7:00 AM in response to MrHoffman

I am well aware of that but some people don't know this.

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