Correct Answer:
C. SMTP
The correct network protocol used to send email is SMTP, which stands for Simple Mail Transfer Protocol. SMTP is the industry-standard protocol for sending emails across the Internet. When you compose and send an email from your email client (e.g., Outlook, Gmail), your client communicates with your outgoing mail server using SMTP. This server then uses SMTP to relay the email to the recipient's mail server, which ultimately delivers it to the recipient's inbox. SMTP is solely responsible for the transmission aspect of email, ensuring messages are routed to their destination.
- A: POP3: Post Office Protocol version 3 (POP3) is used for retrieving emails from a mail server to a local email client. It allows users to download messages from the server, often deleting them from the server after download. It is for receiving, not sending, emails.
- B: FTP: File Transfer Protocol (FTP) is a network protocol used for transferring computer files between a client and server on a computer network. It is specifically designed for file transfers and is unrelated to email communication.
- D: SSH: Secure Shell (SSH) is a cryptographic network protocol used to operate network services securely over an unsecured network. It is commonly used for secure remote login, remote command execution, and secure file transfer (SFTP), but not for sending emails.