Within a secure messaging environment, a determination is made that a request to send a message has been generated by a user. A message protection policy configured to process the message within the secure messaging environment is identified. The message protection policy specifies that, within the secure messaging environment, a secured digital certificate, other than a user-assigned digital certificate of the user, is configured with an associated private key to digitally sign the message on behalf of the user. Based upon the message protection policy, a determination is made to digitally sign the message using the private key of the secured digital certificate. The message is signed on behalf of the user using the private key of the secured digital certificate.