If you are not able to add an Office365 account in outlook. You need to clear the Office registry. Close all office products and rename this registry key: HKEY_Current_User\Software\Microsoft\Office You will see cleared all outlook profiles. So you can fresh start the setup. Now try to add the Office365 account using Mail in the control panel. Another thing to check is if you have SSO enabled with an ADsync Server. Check out this article: https://learn.microsoft.com/en-us/azure/active-directory/hybrid/how-to-connect-sso-quick-start Added the site listed in the GPO section to my intranet zone.
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