User Configuration > Administrative Templates > Microsoft Outlook 2016 > Account Settings > Exchange
User
HKCU\software\policies\microsoft\office\16.0\outlook\rpc
This policy setting specifies the required certificate principal name for the RPC proxy server for Outlook Anywhere. If you enable this policy setting, you must enter a server principal name. You must precede the server name with "msstd:" for this configuration to work. For example, you would enter the following text if the server principal name is mail.fourthcoffee.com: msstd:mail.fourthcoffee.com If you disable or do not configure this setting, Outlook uses the certificate principal name that is specified in Autodiscover.