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Suppress AutoDiscover redirect warning in Outlook

  • Article
  • 03/28/2025
  • Applies to: Outlook 2021, Outlook 2019, Outlook 2016, Outlook for Microsoft 365

Original KB number:   2480582

When Microsoft Outlook redirects an AutoDiscover operation from HTTP to HTTPS, you might receive a warning that resembles the following message:

Allow this website to configure user1@contoso.com server settings?
https://mail.cpandl.com/autodiscover/autodiscover.xml
Your account was redirected to this website for settings.
You should only allow settings from sources you know and trust.

When this warning message occurs, you can choose not to be asked about the specific website again.

If a specific HTTP redirection is expected in your organization, you can suppress the warning message for that website.

Configure Outlook to allow connection to a specific endpoint

Important

This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For protection, back up the registry before you modify it so that you can restore it if a problem occurs. For more information about how to back up and restore the registry, see How to back up and restore the registry in Windows.

To configure the Outlook behavior when HTTP redirection occurs, you can set or deploy a registry value. Use the following steps:

  1. Close Outlook.
  2. Start Registry Editor.
  3. Locate and then select the following registry subkey:
    HKEY_CURRENT_USER\Software\Microsoft\Office\<xx.0>\Outlook\AutoDiscover\RedirectServers

NOTE: You can also use the following registry subkey:
HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\<xx.0>\Outlook\AutoDiscover\RedirectServers
where <xx.0> is 16.0 for Outlook 2021, Outlook 2019, Outlook 2016, and Outlook for Microsoft 365. 4. Select the Edit menu, point to New, and then select String Value. 5. Type the name of the HTTPS server to which the AutoDiscover service can be redirected without prompting for a confirmation from the user, and then press Enter. For example, to allow redirection to https://adatum.com, use adatum.com as the name for the first String Value (REG_SZ). 6. Leave the Value data box empty. The Data column should remain empty for the string values that you create. 7. To add other HTTPS servers to which the AutoDiscover service can be redirected without displaying a warning, repeat steps 4 and 5 for each server. 8. On the File menu, select Exit to exit the Registry Editor.