Prevent users from customizing attachment security settings: registry value disallowattachmentcustomizationUserHKCU\software\policies\microsoft\office\16.0\outlook

Policy ID: L_Preventusersfromcustomizingattachmentsecuritysettings
Scope: User Configuration
Supported on: At least Windows Server 2008 R2 or Windows 7
Source: Microsoft 365 Apps / Office Administrative Templates (version 5568.1000)
Category: Microsoft Outlook 2016 › Security

Registry

disallowattachmentcustomization

REG_DWORDUser

HKCU\software\policies\microsoft\office\16.0\outlook Current key

Enabled value: 1

Apply with .reg · CMD · PowerShell

Enabled

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\software\policies\microsoft\office\16.0\outlook]
"disallowattachmentcustomization"=dword:00000001

CMD · Enabled

reg add "HKCU\software\policies\microsoft\office\16.0\outlook" /v "disallowattachmentcustomization" /t REG_DWORD /d 1 /f

PowerShell · Enabled

New-Item -Path 'HKCU:\software\policies\microsoft\office\16.0\outlook' -Force | Out-Null
New-ItemProperty -Path 'HKCU:\software\policies\microsoft\office\16.0\outlook' -Name 'disallowattachmentcustomization' -PropertyType DWord -Value 1 -Force | Out-Null