ActiveX One-Off forms must be configured.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-228435	SRG-APP-000210	DTOO234	SV-228435r508021_rule	2022-03-11	2

Description
By default, third-party ActiveX controls are not allowed to run in one-off forms in Outlook. You can change this behavior so that Safe Controls (Microsoft Forms 2.0 controls and the Outlook Recipient and Body controls) are allowed in one-off forms, or so that all ActiveX controls are allowed to run.

ℹ️ Check
Verify the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2016 -> Security "Allow Active X One Off Forms" is set to "Enabled: Load only Outlook Controls". Procedure: Use the Windows Registry Editor to navigate to the following key: HKCU\Software\Policies\Microsoft\Office\16.0\outlook\security Criteria: If the value AllowActiveXOneOffForms is REG_DWORD = 0, this is not a finding.

ℹ️ Check

Verify the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2016 -> Security "Allow Active X One Off Forms" is set to "Enabled: Load only Outlook Controls". Procedure: Use the Windows Registry Editor to navigate to the following key: HKCU\Software\Policies\Microsoft\Office\16.0\outlook\security Criteria: If the value AllowActiveXOneOffForms is REG_DWORD = 0, this is not a finding.

✔️ Fix
Set the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2016 -> Security "Allow Active X One Off Forms" to "Enabled: Load only Outlook Controls".