Policy
Send all signed messages as clear signed messages
This policy setting controls whether Outlook sends signed messages as clear text signed messages. If you enable this policy setting, the "Send clear text signed message when sending signed messages" option is selected in the E-mail Security section of the Trust Center. If you disable or do not configure this policy setting, when users sign e-mail messages with their digital signature and send them, Outlook uses the signature's private key to encrypt the digital signature but sends the messages as clear text, unless they are encrypted separately.
e347e1c28e4a L_Sendallsignedmessagesasclearsignedmessages Registry
Copy registry mappings
HKCU\software\policies\microsoft\office\16.0\outlook\security\clearsign (enabled) = 1
HKCU\software\policies\microsoft\office\16.0\outlook\security\clearsign (disabled) = 0Policy notes
This policy setting controls whether Outlook sends signed messages as clear text signed messages. If you enable this policy setting, the "Send clear text signed message when sending signed messages" option is selected in the E-mail Security section of the Trust Center. If you disable or do not configure this policy setting, when users sign e-mail messages with their digital signature and send them, Outlook uses the signature's private key to encrypt the digital signature but sends the messages as clear text, unless they are encrypted separately.