If your mailbox is hosted at SwissCenter (for example a Hosted Exchange mailbox) while your domain is also registered in Microsoft 365, Outlook may keep trying to connect to Microsoft 365 instead of our server. Disabling this automatic detection (Autodiscover) towards Microsoft 365 in the Windows registry prevents it.
In short: in Registry Editor, on the HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Autodiscover key, use New > DWORD (32-bit) Value to create the value ExcludeExplicitO365Endpoint with the data 1, then close and reopen Outlook.
Prerequisites
- Outlook for Windows, version 2016 or later (Outlook 2019, 2021, 2024 or Microsoft 365 Outlook): these versions read their settings under the
16.0 registry key.
What you need to know before you start
- A mistake in the registry can disrupt Windows or your software. Only change the key given below. As a precaution, first select the key, then use File > Export in Registry Editor to keep a copy of it.
- The setting only applies to your Windows session: repeat it on each computer and for each user concerned.
How do I edit the registry?
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In the search field located in the taskbar, type regedit and press Enter.
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In Registry Editor, select the following key in the left pane: HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Autodiscover
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Right-click the key.
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Click New > DWORD (32-bit) Value. The DWORD value is created.
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Name the DWORD value as follows: ExcludeExplicitO365Endpoint
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Double-click the newly created DWORD value. The Edit DWORD (32-bit) Value window opens.
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In the Value data field, enter the value 1 and click OK.
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Close Outlook, then open it again.
The Autodiscover feature for Microsoft 365 is now disabled. If you had already configured a profile and, if applicable, an email account, configure them again.
Troubleshooting
- The
Autodiscover key does not exist: right-click the Outlook key (above it), choose New > Key and name it Autodiscover, then resume at step 3.
- Outlook still connects to Microsoft 365: check the exact name of the value (
ExcludeExplicitO365Endpoint, without spaces) and its data (1), then remove and recreate the account in Outlook.
Going further