S/MIME (Secure/Multipurpose Internet Mail Extensions) is an encryption protocol for emails that allows users to send and receive messages securely. Every user who wants to use S/MIME needs a certificate issued by a certification authority. This certificate contains a public key that is used for encrypting messages. When a user sends an encrypted email to another user, the message is encrypted with the recipient's public key. The recipient can then decrypt the message with their private key and read it. In this way, the messages remain secure and protected from unauthorized access.
