01
Prove the account elsewhere
Confirm the user can sign in to Microsoft 365 or Outlook on the web before treating the problem as a mailbox failure.
Everyday IT · Mobile Email
When Windows works but Apple Mail stops syncing.
Password, MFA, and Conditional Access changes can leave a mobile mail client with stale authentication even while the Microsoft 365 mailbox is healthy.Prove the mailbox first, then refresh the device's Exchange relationship.
02
Refresh iPhone or iPad Mail
In the Exchange account settings, toggle Mail off, wait briefly, and turn it back on. If that does not recover sync, move to a controlled account re-add.
03
Re-add with Microsoft sign-in
Remove the Exchange account, reboot, then add it back using the normal Microsoft sign-in flow so modern authentication and MFA can complete.
04
macOS follows the same logic
Disable Mail for the Exchange account, quit Mail, re-enable it, and if necessary remove and re-add the account through Microsoft sign-in.
Do not reset a healthy mailbox because one device has stale authentication.