The operation couldn’t be completed. (com.apple.accounts error 3.)

This issue shows as resolved on the MS status page buts its still happening this evening for me.

try clearing your outbox and then check. It worked for me after that.

same issue here, any updates on this?

Seems MS are suggesting it's a specific Apple Mail / macOS issue. Just for fun, are people with the issue running the latest Tahoe beta? I am and experiencing this issue. Wasn't on the previous build. Haven't A/B'd.

Below reply to my MS support ticket, if helpful for others:

'Based on the investigation, the issue you are experiencing is coming from the Apple Mail application itself. The specific error message displayed “The operation couldn’t be completed (com.apple.accounts error 3)”  is generated by the Apple Internet Accounts framework in macOS. This component is fully developed and maintained by Apple, and the failure occurs after Microsoft has already completed the sign‑in and multifactor authentication process successfully. Since the problem happens within Apple’s authentication framework and not within Microsoft 365 services, this falls outside Microsoft’s support scope, and Apple Support would need to be involved to continue troubleshooting.  

I also confirmed that the Microsoft authentication flow is working correctly. The Microsoft sign‑in page loads as expected, MFA push notifications are delivered, and approval requests are successfully completed. This confirms that your Microsoft account and the authentication service are functioning normally. The Conditional Access logs you provided also indicate that the policies are behaving as intended, requiring strong authentication and device identity. Apple Mail, however, often struggles to meet these requirements, especially when device compliance or modern security controls are enforced.  

Regarding the historical incident you mentioned from November/December 2025, I have verified the status of that event, and it is fully resolved. There is no current Microsoft 365 service issue affecting the Apple Mail or macOS Internet Accounts connection flow.  

It is also important to note that Outlook for Mac is working without any issues in your environment, which further confirms that Microsoft 365 services are healthy and that the problem lies specifically with Apple Mail. Outlook is fully compatible with Conditional Access and modern authentication, which is why it continues to function normally.  

At this stage, the recommended next step is to contact Apple Support and provide them with the error code, the macOS logs, and the confirmation that Microsoft authentication completes successfully on your side. In the meantime, using Outlook for Mac remains the supported and reliable method for accessing your Microsoft 365 mailbox.'

Hello,

I wanted to share how I solved this because of no documentation anywhere and MS support that was not able to locate the issue.

Apple Mail for MacOS uses EWS.

Apple Mail for IOS ActiveSync.

I was getting error 3 on every macbook I owned for every account of my ORG.

After discovering that Apple mail uses EWS I checked the status of it using Exchange Online PowerShell, turns out it was disabled.

When configuring 365 for the first time Microsoft suggests you to disable it as they are going to deprecate it in a few months, so you’ll probably have to re-enable it through the PowerShell if you followed the suggestion, both for the organization and for every user.

NOTE: Even if the users have it enabled in the allowed apps under the Mail section it could be still disabled ORG wide.

After doing so it will take a few hours to work; if it does not after 24 hrs ask MS support to run a diagnostic on EWS and on every account of your ORG, that should do the trick.

Suggetion: to check whether EWS is enabled for the account and it is working use Thunderbird, which allows to specifically choose EWS as connection method for MS 365 accounts.

Enjoy