4.Do one or both of the following:
To sign all your outgoing email messages so that recipients can be certain that the messages were sent by you and have not been altered in any way, select the Sign all outgoing email messages check box.
To encrypt all your outgoing email messages so that the contents of your messages are protected from being viewed by anyone other then the intended recipients, select the
Encrypt all outgoing email messages check box.
5.Tap Choose Certificate to select a certificate for signing or encrypting outgoing email messages. You can select certificates to sign or encrypt email messages individually if you do not choose to sign or encrypt all outgoing email.