Back and forth between Microsoft and Apple: Cannot add Microsoft-hosted email to Apple Mail

Question

Back and forth between Microsoft and Apple: Cannot add Microsoft-hosted email to Apple Mail

Matthew Leung 0

Tried many troubleshooting on both MacOS and MS365:

Mac:

Can add account on iOS, but not MacOS
Keychain delete
Add / Removed account
Custom SMTP server
No VPN on
Deleted Mail cache folders

Microsoft:

EWS enabled
App registrations enabled
Outlook.com working
Outlook client working
Thunderbird working
Other Exchange servers can be added to Apple Mail, no problem
Disabled all POP, SMTP, etc. and re-enabled them
Tried all sorts of MFA configurations

After going through all these settings still:

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2 answers

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Answer 1

Anonymous

Hi @Matthew Leung

Thank you for posting your question in the Q&A Forum and sharing all the troubleshooting you’ve already completed. That really helps in understanding how this is behaving in your environment.

From what you’ve described, the mailbox works normally across Outlook on the web and desktop, iOS Mail, and Thunderbird. This shows the account and Microsoft 365 service are functioning as expected.

The difference appears when adding the account to Apple Mail on macOS. In this case, the Mail app depends on system-level components like local Mail profiles, cached credentials, and Keychain data. These are managed by macOS and can affect how the Exchange connection is established or stored, which Microsoft 365 does not have visibility into.

A practical next step would be to try adding the account under a new macOS user profile. This can help determine whether the behavior is tied to your current user environment or to macOS Mail more broadly. If the issue persists in a clean profile, Apple Support would be best placed to review Mail and Keychain behavior at the OS level.

Meanwhile, using Outlook for Mac or Outlook on the web will let you continue working while the macOS Mail behavior is being investigated. We appreciate the detailed information you’ve provided, as it really helps give the clearest guidance possible from a forum perspective.

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Matthew Leung 0 Reputation points

2026-01-05T15:55:09.0666667+00:00

Apple is sure it is a setting in MS365.
Matthew Leung 0 Reputation points

2026-01-05T15:57:44.3+00:00

I added other mail accounts from other MS365 tenants perfectly fine.
Matthew Leung 0 Reputation points

2026-01-05T16:17:23.85+00:00

Message in health centre:

"Some admins or users may be unable to access multiple Microsoft 365 services"
Anonymous

2026-01-07T01:49:08.43+00:00

Hi @Matthew Leung

Thank you for the additional context. The fact that other tenants work perfectly on the same Mac confirms that the macOS Mail client and the Microsoft 365 service are globally operational.

Since this behavior is isolated to this specific tenant, it suggests a configuration mismatch (such as Conditional Access, MFA requirements, or Modern Auth policies) specific to this organization.

As forum moderators, we do not have administrative access to your private tenant’s Entra ID (Azure AD) sign-in logs. If you are managing this tenant, we recommend checking the logs for this specific user's login attempts. The logs will show exactly if the request is being 'Interrupted' or 'Failed' due to a specific policy.

If the logs show a 'Success' but the Apple Mail client still fails to sync, it indicates a local token handling issue, and a new macOS user profile remains the best test to isolate the local environment.

For deeper tenant-level investigation, please open a formal support ticket via the Microsoft 365 Admin Center, as they have the tools to analyze your specific backend configuration.
Matthew Leung 0 Reputation points

2026-01-21T22:16:17.33+00:00

I remember. This issue happened when I allowed Microsoft to set the baseline security. Even when I turn off baseline security, I cannot login to mail.
Anonymous

2026-01-22T02:40:50.0333333+00:00

Hi @Matthew Leung

Thank you for confirming that this behavior started with the Security Defaults transition. This helps us focus the investigation on a tenant-level authentication state rather than a general software behavior.

Since disabling the baseline security didn't immediately restore access, it's likely that a stale authentication token or a propagation delay is still affecting your specific tenant. Please ensure you have tried to Revoke MFA sessions for the affected user in the Entra admin center to force a complete re-authentication and clear all Microsoft-related entries in macOS Keychain to ensure no old tokens are being reused.

Because this now involves investigating private tenant-wide policies and back-end authentication logs which contain sensitive information, we cannot proceed further over a public forum for your security.

The most effective next step is to raise a support ticket via the Microsoft 365 Admin Center. This allows a support engineer to securely review your tenant’s sign-in logs and ensure the Security Defaults change has been fully synchronized across all services.

We appreciate your patience and cooperation throughout the troubleshooting process.

Answer 2

It seems you have already performed a comprehensive set of troubleshooting steps on both macOS and Microsoft 365. Here are a few additional considerations that might help you resolve the issue of adding a Microsoft-hosted email to Apple Mail on macOS:

Autodiscover Configuration: Ensure that the Autodiscover service is properly configured for your domain. If there are issues with the Autodiscover service, it can prevent proper account setup in Apple Mail.
Certificate Issues: Check if there are any SSL certificate issues. The certificate must match the domain and be trusted by the macOS system.
Account Type: Make sure you are selecting the correct account type when adding the email account in Apple Mail. For Microsoft-hosted email, you typically want to use Exchange.
Network Settings: Verify that there are no network settings or firewalls that might be blocking the connection to the Microsoft Exchange server.
Logs and Console: Check the Console app on macOS for any error messages related to Mail when you attempt to add the account. This might provide more insight into what is going wrong.
Updates: Ensure that both macOS and any relevant applications (like Apple Mail) are fully updated to the latest versions, as updates can resolve compatibility issues.

If these steps do not resolve the issue, you may want to reach out to Microsoft support for further assistance, as they may have more specific insights into account configurations and issues related to Exchange Online.

References:

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Back and forth between Microsoft and Apple: Cannot add Microsoft-hosted email to Apple Mail

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