Why has my Outlook mail suddenly stopped connecting to my MacBook Pro mail app

Justin Cockerill 35 Reputation points
2026-02-04T21:30:35.7833333+00:00

For some reason, my MacBook Pro can no longer connect to Outlook Mail (using Exchange). It just happened yesterday totally unexpectedly. I have restarted my MacBook ... that didn't help. I deleted the account and then added it again ... my email address was accepted and a "single-use code" was sent to me and it was accepted too. I can log in to my Outlook Mail using a web address, but not using my Mac's Mail App. Please help!

Outlook | MacOS | New Outlook for Mac | For home
Answer accepted by question author
Chloe-L 13,685 Reputation points Microsoft External Staff Moderator
2026-02-05T23:21:33.9733333+00:00

Hello Justin Cockerill,

Thank you for posting to the Microsoft Q&A.

I understand how disruptive it is when your email sync suddenly breaks unexpectedly, especially when you rely on the convenience of the Mac Mail app for your daily workflow.

I am aware that Apple released a new update on Monday the 26th which appears to have disrupted the Outlook authentication tokens for some users. Essentially, the update may have invalidated the existing security token between your Mac and the Exchange server.

Note: Some users have reported that this issue resolved itself automatically after 24 hours as the services eventually re-synced. If you can afford to wait, you might check back tomorrow. However, if you need access immediately, you can try the steps below to force a fix.

Step 1: Clear the "Exchange" Entries in Keychain

  1. Close the Mail app completely (Right-click icon > Quit).
  2. Open Spotlight Search (Command + Space) and type "Keychain Access". Open the app.
  3. In the search bar at the top right, type "Exchange" (or "Office" if nothing comes up).
  4. Look for any entries related to your email address or com.microsoft.exchange.
  5. Right-click and Delete these specific entries.
  6. Restart your Mac after deleting them to flush the cache.

Step 2: Re-add using the "Microsoft Exchange" Protocol

  1. Open System Settings (or System Preferences) > Internet Accounts.
  2. Click Add Account.
  3. Select Microsoft Exchange (Do not select "Outlook.com" or "Other Mail Account"
  4. Enter your email and sign in. It should now prompt you for the code/password and create a fresh token.

Since many users are experiencing this friction recently, I highly recommend submitting feedback directly to Microsoft so their engineering team can investigate the root cause of this token expiration. You can do this by going to Help > Feedback in any Office app or via the Feedback Portal.

I sincerely hope that clearing the Keychain entries resolves the conflict and gets your inbox syncing again. Please let me know if the account connects successfully after the restart. Thank you for your understanding.

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Was this answer helpful?

1 person found this answer helpful.

1 additional answer

Sort by: Most helpful
Most helpful Newest Oldest

  1. AI answer

    2026-02-04T21:30:44.3033333+00:00

    It seems you are experiencing connection issues with your Outlook Mail app on your MacBook Pro. One possible reason for this issue is that Outlook may not support connections to Exchange using certain protocols or settings. Here are a few steps you can take to troubleshoot the problem:

    1. Check Connection Settings: Ensure that you are using the correct settings to connect to your Exchange account. Outlook typically requires standard Exchange connection settings rather than ActiveSync.
    2. Update Outlook: Make sure that your Outlook app is updated to the latest version, as updates can fix bugs and improve connectivity.
    3. Check for Basic Authentication: If your organization has disabled Basic authentication, you may need to ensure that your account settings are compatible with Modern authentication for Outlook.
    4. Re-add Account: Since you already tried deleting and re-adding the account, ensure that you follow the correct steps as per the official guidelines for adding an email account to Outlook.
    5. Check Internet Connection: Confirm that your MacBook has a stable internet connection, as connectivity issues can also prevent the app from connecting to the mail server.

    If these steps do not resolve the issue, you may want to consider reaching out to your IT support or Microsoft support for further assistance.

    References:

    AI-generated content may be incorrect. Read our transparency notes for more information.

    Was this answer helpful?

Your answer

Answers can be marked as 'Accepted' by the question author and 'Recommended' by moderators, which helps users know the answer solved the author's problem.