What is S/MIME ?
S/MIME (Secure/ Multipurpose Internet Mail Extensions) is a de facto standard for sending secure e-mail over the Internet. MIME is the industry standard format for electronic mail, which defines the structure of the message’s body. S/MIME adds a secure feature to the MIME standard. E-mail applications that support S/MIME add digital signatures and encryption capabilities to that format. Standardisation of the secured message’s format allows users to conduct private and authenticated communications, independent of the e-mail software they use, as long as this software is S/MIME compatible. You and your recipient must have public key certificates and S/MIME compatible e-mail applications in order to send and receive secured e-mail.