CREST Practitioner Security Analyst (CPSA) Practice

What function does the Post Office Protocol version 3 (POP3) serve?

1. Sending emails

2. Receiving emails

3. Synchronizing time

4. Executing remote commands

The correct answer is: Receiving emails

The Post Office Protocol version 3 (POP3) is primarily designed for receiving emails. It allows email clients to retrieve emails from a mail server. When a user connects to the server using POP3, the protocol facilitates the downloading of messages to the user's device, enabling offline access to their emails. POP3 operates on a client-server model where the client requests emails and the server responds by providing the messages stored. Once emails are downloaded, they can typically be deleted from the server, which is key for users who prefer to store their emails locally rather than on the server. This functionality is distinct from the roles of sending emails (handled by protocols like SMTP), synchronizing time (managed by protocols such as NTP), and executing remote commands (which can be accomplished using protocols like SSH). Thus, POP3's role as a retrieval method aligns precisely with its definition and purpose in email communication.