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As i know: When Microsoft Outlook redirects an AutoDiscover operation from HTTP to HTTPS, you may receive a warning message that resembles the following:
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 may choose not to be asked about the specific website again. (That is, it is recommended to select 'Allow'.)
In addition, if you want to suppress the initial warning message for a specific HTTP redirection, you may need to modify the registry. More information: How to suppress AutoDiscover redirect warning - Outlook | Microsoft Learn
(Note: Serious problems can occur if you modify the registry incorrectly. Before making changes, back up the registry to restore it in case something goes wrong.)
Hope it helps!
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