Knowledgebase: Microsoft Outlook
Disable Office365 Sign-in/Autodiscovery When Using On-Premise Exchange with Office365 Apps
Posted by Christopher P., Last modified by Christopher P. on May 25, 2022 01:24 PM

If your organization is using Office365 application suite (such as Word, Excel, Outlook, PowerPoint, etc) but still using an on-premise Exchange server for your emailing system, sometimes the Outlook desktop client can attempt to try and use the cloud Office365 services instead of your local on-premise system.

To correct this, there are a few things we can try.

Create New Profile

First, we can attempt to create a new Outlook profile. This often will resolve any issues. To do this:

  1. Close any Outlook windows.
  2. Navigate to the Control Panel
  3. Open the Mail or Mail (32-bit) control panel applet.
  4. Click Show Profiles...
  5. Click Add... and give it a name (for example, prf1)
  6. In the wizard that appears, click Next as needed until the info is verified and Finish when it's done
  7. In the Mail applet, click on Always use this profile
  8. Select the new profile that you just created from the list
  9. and click OK.

When finished, re-open the Outlook desktop client. Hopefully everything should work as intended now and be connected to the on-premise Exchange services. If not, try the next possible solution where we make some registry adjustments.

Registry Adjustments

The next step we can try is to make some registry adjustments.

  1. Close any Outlook windows.
  2. In the Windows registry, perform the following:
    1. Remove all values at HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\AutoDiscover\RedirectServers
    2. Add the following REG_DWORD values:
      • At HKEY_CURRENT_USER\Software\Microsoft\Exchange, add AlwaysUseMSOAuthForAutoDiscover = 1
      • At HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\AutoDiscover, add ExcludeExplicitO365Endpoint = 1

When finished, re-open the Outlook desktop client. Everything should work as intended now and be connected to the on-premise Exchange services.

Note: If you are prompted to sign-in for the first time (typically this happens when a new user is created and hasn't created an Outlook profile yet), enter your email address and when it says to select the Account Type, select Exchange, and follow the prompts to finish the sign-in. Once Outlook opens, everything should be all set.

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