This policy setting controls whether replies and forwards to signed/encrypted mail should also be signed/encrypted. If you ...

This policy setting controls whether replies and forwards to signed/encrypted mail should also be signed/encrypted.  If you enable this policy setting, signing/encryption will be turned on when replying/forwarding a signed or encrypted message, even if the user is not configured for SMIME.If you disable or do not configure this policy setting, signing/encryption is not enforced.