Always use TNEF formatting in S/MIME messages

Category

User Configuration > Administrative Templates > Microsoft Outlook 2016 > Security > Cryptography

Scope

User

Registry Key

HKCU\software\policies\microsoft\office\16.0\outlook\security

Description

This policy setting allows you to specify the formatting when sending S/MIME messages. If you enable this policy setting, Outlook always uses TNEF formatting when sending S/MIME messages. If you disable or do not configure this policy setting, Outlook uses the format specified by the user when sending e-mail messages, including when sending S/MIME messages.