Information
This policy setting controls whether Outlook prompts users before executing a custom action. Custom actions add functionality to Outlook that can be triggered as part of a rule. Among other possible features, custom actions can be created that reply to messages in ways that circumvent the Outlook model's programmatic send protections.
The recommended state for this setting is: Enabled: Automatically Deny
Malicious code can use the Outlook object model to compromise sensitive information or otherwise cause data and computing resources to be at risk.
Solution
To establish the recommended state via configuration profiles, set the following Settings Catalog path to Enabled: Automatically Deny :
Microsoft Outlook 2016\Security\Security Form Settings\Outlook Security Mode > Set Outlook object model custom actions execution prompt
Important: For this setting to apply, the
Outlook Security Mode
setting must be enabled in
Microsoft Outlook 2016\Security\Security Form Settings
with Use Outlook Security Group Policy selected, as set in this benchmark.
Impact:
Configuring this setting to Automatically Deny prevents Outlook from executing any custom actions that use the Outlook object model. Users will not be able to utilize this function.