Which application layer protocol is used for email retrieval from a mail server?

• A. Post Office Protocol (POP)
• B. Simple Mail Transfer Protocol (SMTP)
• C. Internet Message Access Protocol (IMAP)
• D. File Transfer Protocol (FTP)

Answer: (A)

Retrieving email from a mail server is handled by a protocol that focuses on pulling messages to the client. Post Office Protocol (POP) is designed for this purpose: the client connects, authenticates, downloads messages from the server, and, depending on settings, may delete them from the server after download. This makes POP a straightforward choice when the goal is to fetch mail to a single device and go offline with copies.

IMAP is another retrieval option, but it’s built for keeping messages on the server and synchronizing the mailbox across multiple devices, which is different from the simple download-and-offload model POP uses. SMTP, on the other hand, is used for sending mail from a client to a mail server or between servers, not for retrieving it. FTP is a file-transfer protocol and isn’t used for email retrieval at all.

So, for the task of retrieving email from a server, POP is the appropriate protocol.