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How to fix Outlook disconnected after migrate to Exchange Online

After migrating from Exchange 2010 to Exchange Online, Outlook might still try to connect to the old server. To swiftly resolve the issue of Outlook not redirecting to Exchange Online after mailbox migration, follow these steps.

How to fix Outlook disconnected after migrate to Exchange Online

Solution 1: Uncheck “Always use my Windows credentials”

  1. Close Outlook completely.
  2. Open Control Panel > Mail > Email Accounts.
  3. Select your account > Change > More Settings > Security.
  4. Uncheck “Always use my Windows credentials”.
  5. Click OK, Next, Finish.
  6. Restart Outlook.

Solution 2: Check Autodiscover Settings

Ensure Autodiscover is pointing to Exchange Online.

  1. Open Outlook and hold down the Ctrl key while right-clicking the Outlook icon in the system tray.
  2. Select Test E-mail AutoConfiguration.
  3. Enter the user’s email address and password, uncheck Use Guessmart, and click Test.
  4. Verify that the Autodiscover service URL is correct and points to Exchange Online.

Solution 3: Update DNS Records

Confirm that DNS records (MX, CNAME, etc.) are correctly configured for Exchange Online. Particularly, the CNAME record for Autodiscover should be set to autodiscover.outlook.com.

Solution 4: Remove old Exchange server from Outlook profile

  1. Go to Control Panel > Mail > Show Profiles
  2. Remove the old Exchange server entry from the profile
  3. This prevents Outlook from attempting to connect to the decommissioned server

Solution 5: Remove Old Outlook Profiles

Sometimes old profiles can cause issues. Create a new profile to ensure settings are fresh.

  1. Go to Control Panel > Mail > Show Profiles > Add.
  2. Set up the new profile and set it as the default.
  3. Remove the old Exchange server entry from the profile

Solution 6: Create a new Outlook profile

Sometimes old profiles can cause issues. Create a new profile to ensure settings are fresh.

  1. Open Outlook and navigate to File > Account Settings > Manage Profiles
  2. Create a new profile and add the user’s Exchange Online account
  3. Set up the new profile and set it as the default.

Solution 7: Check Licenses and Permissions

Ensure the user has a valid Business Standard license assigned. Verify mailbox migration is complete and no data sync is pending.

Solution 8: Registry Key Modification

In some cases, modifying registry keys can force Outlook to connect correctly.

  1. Press Windows + R.
  2. Type: regedit
  3. Navigate to HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\AutoDiscover
  4. Right-click > New > DWORD (32-bit) Value
  5. Name it: ExcludeHttpRedirect
  6. Set value to 1.
  7. Restart Outlook.

Solution 9: Update Outlook to the latest version

Outdated Outlook versions may face compatibility issues with Exchange Online. Upgrading to the latest version ensures optimal performance and connectivity.

Go to File > Office Account > Update Options > Update Now.

Solution 10: Clear Outlook cache

  1. Close Outlook.
  2. Delete the OST file from the user’s AppData folder
  3. Restart Outlook to rebuild the cache and sync with Exchange Online

Solution 11: Repair Outlook

Sometimes a quick repair can resolve connectivity issues.

  1. Go to Control Panel > Programs and Features > Microsoft Office > Change.
  2. Select Quick Repair and follow the prompts.

By implementing these steps, you’ll successfully redirect Outlook to Exchange Online, establishing a seamless connection for the user. Remember to test the connection and verify that emails are syncing correctly. If issues persist, engage Microsoft Support for further assistance.