MacBook Mail Client Authentication Issue – com.apple.accounts Error 3

The Mail client is not working on the MacBook, although the same email account works correctly on the mobile phone.

When entering the email credentials on the MacBook, Microsoft 365 authentication completes successfully. However, after successful O365 authentication, the Mail client displays the following error:

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

Could you please check the issue and advise on the required configuration or resolution?

Posted on Oct 6, 2026 1:55 AM

1 reply

kaz-k

Level 9 (53,902 points)

Oct 6, 2026 10:00 AM in response to vishmi225

Hi,

To fix com.apple.accounts error 3 in Apple Mail on your MacBook Pro, remove the corrupted account and re-add it through Apple Support guidelines or the official Microsoft Q&A Guide.

Steps to Resolve Error 3

Remove the Account: Open the Mail app, go to Settings or Accounts, select your broken account (often Microsoft Exchange), and click the minus (-) button to delete it.
Restart Your Mac: Reboot your computer to clear out temporary system cache and corrupted local credential storage.
Re-Add the Account: Go to System Settings > Internet Accounts (or Mail > Accounts), click the plus (+) sign, and choose your provider (like Microsoft Exchange).
Sign In via OAuth: Enter your email address, complete the organization's pop-up sign-in authentication window, and select Mail when prompted what apps to sync.