Configure Simple MAPI message opening prompt
Supported on: At least Windows Server 2008 R2 or Windows 7
Registry
HKCU
software\policies\microsoft\office\16.0\outlook\security Options
promptsimplemapiopenmessage enum - Prompt User
->
1 - Automatically Approve
->
2 - Automatically Deny
->
0
Description
This policy setting allows you to specify what occurs when a program attempts to gain access to a recipient field, such as the “To” field, using Simple MAPI. If you enable this policy setting, you can choose whether Outlook always allows access to the recipient field, always disallows access to the recipient field, or prompt users to specify whether to allow or disallow access to the recipient field. If you disable or do not configure this policy setting, Outlook prompts users to specify whether to allow or disallow access to the Address Book.