How to fix macOS Mail app failing to authenticate with Microsoft 365 after password change

Summary

This guide helps you troubleshoot and resolve: How to fix macOS Mail app failing to authenticate with Microsoft 365 after password change. Follow the steps below to fix the issue.

Common Causes

If you have recently changed your Microsoft 365 password, the Mail app on macOS may continue to prompt you for credentials or fail to send and receive messages. This happens because the app is still using the stored authentication token from your previous password. Follow the steps below to re-authenticate your account and restore mail functionality.

Quick Fix Steps

1. Quit the Mail app completely.
2. Open System Settings and navigate to Internet Accounts.
3. Select your Microsoft 365 account and remove it.
4. Re-add the account using your updated password.
5. Restart the Mail app and test sending and receiving messages.

Detailed Instructions

Remove the Microsoft 365 Account

1. Open the Apple menu and select System Settings.
2. Scroll down the left-hand sidebar and click Internet Accounts.
3. Locate your Microsoft 365 or Outlook account in the list on the right.
4. Select the account and click the minus (-) button at the bottom of the list.
5. When prompted, confirm that you want to remove the account.

Re-Add the Account

1. In Internet Accounts, click the plus (+) button.
2. Select Microsoft Exchange from the list of providers.
3. Enter your full Microsoft 365 email address and click Sign in.
4. Enter your updated password when prompted.
5. If Multi-Factor Authentication (MFA) is enabled, complete the verification step using your authenticator app or SMS code.
6. Ensure Mail is toggled on, then click Done.

Verify Mail Functionality

1. Open the Mail app from your Dock or Applications folder.
2. Wait for the account to synchronize. You may see a progress indicator in the sidebar.
3. Send a test email to your own address to confirm outgoing mail is working.
4. Check that new messages arrive in your inbox.

Troubleshooting

Password Prompt Keeps Returning

If Mail continues to ask for your password after re-adding the account, try the following:

• Ensure your Mac is connected to a stable internet connection.
• Restart your Mac and open Mail again.
• Check that your system date and time are correct. Go to System Settings > General > Date & Time and enable Set date and time automatically.
• Remove the account again, restart your Mac, then re-add it.

Mail App is Unresponsive or Crashing

• Force quit Mail by pressing Command + Option + Esc, selecting Mail, and clicking Force Quit.
• Check for macOS updates by going to System Settings > General > Software Update.
• Ensure you are running the latest version of macOS supported by your device.

Tip: If you use the Microsoft Outlook app instead of Apple Mail, you may need to sign out and sign back in there as well after a password change.

Caution: Removing the account from Internet Accounts will also remove associated calendars and contacts synced through that account. These will resynchronize automatically once you re-add the account.

If you continue to experience authentication errors after following these steps, please Open a Ticket with our support team for further assistance.

Still Having Issues?