Configure Outlook object model prompt when reading address information
This per-user `REG_DWORD` value controls how the Object Model Guard in classic Outlook handles programmatic requests to read protected address information through the Outlook object model.
since 0.9.8.11
Purpose
Show registry keys (1)
HKCU\software\policies\microsoft\office\16.0\outlook\security\promptoomaddressinformationaccess
This per-user REG_DWORD value controls how the Object Model Guard in classic Outlook handles programmatic requests to read protected address information through the Outlook object model. Protected information includes sender, recipient, and email address data exposed through certain object-model properties and methods.
The value data has the following meanings:
0: Outlook automatically denies the protected access.1: Outlook displays a security prompt that allows the user to approve or deny the access.2: Outlook automatically approves the protected access.
The setting applies only to read operations covered by this Object Model Guard category. It does not grant a program general mailbox access or permission to send messages automatically.
Notes
Security
A value of 2 removes the security prompt for the affected access requests. Malicious or compromised software capable of automating Outlook could consequently read protected email addresses and recipient information without the user approving each request.
A value of 0 automatically blocks these requests. A value of 1 leaves the decision to the user, but relies on the user being able to assess the requesting application and the reason for the request.
This setting is not a comprehensive access control for Outlook data. It governs only the protected Outlook object-model entry points associated with this policy.
Possible side effects
With a value of 0, legitimate automation and add-ins can fail when they require protected address information and are not otherwise treated as trusted. Microsoft identifies this value as a possible cause of problems involving the Teams Meeting Add-in in classic Outlook.
With a value of 1, security prompts can interrupt interactive workflows. Unattended processes might be unable to continue until a user responds.
Notes
For dependent Outlook security policies to be evaluated, Outlook Security Mode must be set to use Outlook Security Group Policy. In registry-based Group Policy configurations, this corresponds to AdminSecurityMode set to 3.
promptoomaddressinformationaccess is distinct from similarly named settings. Address-book access, sending messages, and retrieving address information through UserProperties.Find are governed by separate policy values.
Microsoft documentation
Microsoft Learn: Microsoft 365 Apps for Enterprise security baseline settings reference
Microsoft Learn: Information about e-mail security settings
Microsoft Learn: Protected Properties and Methods in the Outlook object model
Microsoft Learn: Offline scan forced by Group Policy for Outlook object model access