How to fix macOS Mail app unable to connect to Microsoft 365 Exchange after a password change

Summary

This guide helps you troubleshoot and resolve: How to fix macOS Mail app unable to connect to Microsoft 365 Exchange after a password change. Follow the steps below to fix the issue.

Common Causes

If you have recently changed your Microsoft 365 password, the macOS Mail app may fail to connect to your Exchange account. This happens because the stored credentials are now outdated, causing authentication errors or repeated password prompts. Follow the steps below to update your account settings and restore your email access.

Quick Fix Steps

1. Quit the Mail app completely.
2. Open System Settings.
3. Navigate to Internet Accounts.
4. Select your Microsoft 365 account and remove it.
5. Re-add the account using your new password.
6. Restart the Mail app and verify synchronisation.

Detailed Instructions

Step 1: Quit the Mail app

Ensure the Mail app is fully closed before making changes to your accounts.

1. Click Mail in the top menu bar.
2. Select Quit Mail, or press Command + Q.

Step 2: Open System Settings

1. Click the Apple menu () in the top-left corner of your screen.
2. Select System Settings.

Step 3: Remove the existing Exchange account

1. In the left sidebar, scroll down and click Internet Accounts.
2. Locate your Microsoft 365 or Exchange account in the list on the right.
3. Select the account and click the minus (-) button at the bottom of the list.
4. When prompted, confirm that you want to remove the account.

Step 4: Re-add your Microsoft 365 account

1. With Internet Accounts still open, click the plus (+) button.
2. Select Microsoft Exchange from the list of providers.
3. Enter your full email address and click Sign In.
4. Enter your updated Microsoft 365 password when prompted.
5. Complete any multi-factor authentication steps if required by your organisation.
6. Select which apps you wish to use with this account (Mail, Contacts, Calendars, etc.) and click Done.

Step 5: Verify Mail synchronisation

1. Open the Mail app.
2. Wait a few moments for your inbox and folders to synchronise with the server.
3. Send a test email to yourself to confirm that sending and receiving are working correctly.

Troubleshooting

Mail continues to ask for the old password

If the Mail app continues to prompt for credentials, the macOS Keychain may be storing the outdated password.

1. Open Finder, then go to Applications > Utilities.
2. Double-click Keychain Access.
3. In the search bar at the top right, type your email address or exchange.
4. Locate any entries related to your Microsoft 365 account.
5. Right-click the entry and select Delete.
6. Restart the Mail app and sign in again with your new password.

Account will not verify after re-adding

• Ensure your Mac is connected to the internet.
• Verify that you are entering the full email address (e.g., [email protected]), not just the username.
• If your organisation uses modern authentication, you may be redirected to a Microsoft sign-in page in a browser window. Complete the sign-in process there.

If you are still unable to connect after following these steps, please Open a Ticket with our support team for further assistance.

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