Network Defense Essentials (NDE) 2025 – 400 Free Practice Questions to Pass the Exam

S/MIME, which stands for Secure/Multipurpose Internet Mail Extensions, is the correct protocol for sending encrypted and digitally signed email messages. It is an extension of the MIME protocol, which is used for sending multimedia content over email, but S/MIME adds security features that protect the content of email communication.

The encryption provided by S/MIME ensures that only the intended recipient can read the message, safeguarding it from unauthorized access during transmission. Additionally, S/MIME allows senders to sign their emails digitally, which provides a mechanism for verifying the authenticity of the sender. This dual capability of encryption and digital signatures enhances the security and integrity of email communications.

In contrast, SMTP (Simple Mail Transfer Protocol) is primarily designed for sending emails but does not inherently provide encryption or signing features. POP3 (Post Office Protocol) and IMAP (Internet Message Access Protocol) are protocols used for retrieving emails from a mail server, focusing on how users can access their messages rather than securing the messages themselves. Therefore, S/MIME stands out as the appropriate choice when it comes to securing email communications by providing encryption and digital signatures.