This policy setting controls what happens when an untrusted program attempts to gain access to an Address Book using the ...

This policy setting controls what happens when an untrusted program attempts to gain access to an Address Book using the Outlook object model. 

If you enable this policy setting, you can choose from four different options when an untrusted program attempts to programmatically access an Address Book using the Outlook object model: 

- Prompt user - Users are prompted to approve every access attempt. 
- Automatically approve - Outlook will automatically grant programmatic access requests from any program. This option can create a significant vulnerability, and is not recommended. 
- Automatically deny - Outlook will automatically deny programmatic access requests from any program. 
- Prompt user based on computer security - Outlook will rely on the setting in the "Programmatic Access" section of the Trust Center. This is the default behavior. 

If you disable or do not configure this policy setting, when an untrusted application attempts to access the address book programmatically, Outlook relies on the setting configured in the "Programmatic Access" section of the Trust Center. This setting determines whether Outlook will warn users about programmatic access attempts: 

- Only when antivirus software is out of date or not running (the default setting) 
- Every time 
- Not at all. If the "Not at all" option is selected, Outlook will silently grant programmatic access to any program that requests it. 

Note -  This described default functionality assumes that you have not followed the recommendation to enable the "Outlook Security Mode" Group Policy setting to ensure that Outlook security settings are configured by Group Policy. If Group Policy security settings are used for Outlook, the "Programmatic Access" section of the Trust Center is not used. In this situation, the default is to prompt users based on computer security, which is the equivalent of the "Only when antivirus software is out of date or not running" option in the Trust Center, and the user experience is not affected. 

Important: This policy setting only applies if the "Outlook Security Mode" policy setting under "Microsoft Outlook 2010\Security\Security Form Settings" is configured to "Use Outlook Security Group Policy."

For more information about the Object Model Guard, see Security Behavior of Outlook (http://officeredir.microsoft.com/r/rlidGPSecBehaviorOutlookModelO14?clid=1033) in the MSDN Outlook 2010 Developer Reference.