How to control client SCP look-up in Outlook client test email?

So the best approach here is to use the Registry settings workaround stated in the above Good Workaround post and the below Microsoft Knowledge base article that contains the Registry keywhich will control the Client SCP look-upbehaviorand shows you with a live example using Outlook Client Test Email Autoconfiguration results for reference.

Where can I find the results of an SCP lookup?

The results of an SCP lookup should be at the top of your candidate list. NOTE: SCP lookup isn't available for clients that are not joined to a domain or that do not have access to Active Directory servers. In this case, you should skip SCP lookup.

How do client/service applications use SCPs?

Clients of the service use the data in an SCP to locate, connect to, and authenticate an instance of your service. This section provides an overview of service connection points and code examples that show how a client/service application uses SCPs. The code example follows these steps to implement service publication with SCPs.

What is a SCP pointer?

SCP pointers — These contain information that points to specific LDAP servers that should be used to locate Autodiscover SCP objects for the user's domain. SCP pointers are stamped with the following GUID: 67661d7F-8FC4-4fa7-BFAC-E1D7794C1F68. SCP URLs — These contain URLs for Autodiscover endpoints.