What is the primary function of SMTP?

The primary function of SMTP (Simple Mail Transfer Protocol) is to send and relay email messages across networks. SMTP operates as a communication protocol used by email servers to facilitate the transfer of email from a sender to a recipient. It is essential for the process of delivering email from the sender's email client to the recipient's email server and can relay messages between email servers until they reach their destination.

In this context, SMTP works by establishing a connection between email servers and using a set of commands to effectively transmit email messages. It's important to note that while SMTP handles sending, other protocols, such as POP3 or IMAP, are responsible for retrieving and managing messages once they have been delivered to the recipient's server.

The other options describe functions or capabilities that are not related to SMTP's primary role. For example, storing email messages is typically managed by the email server's storage rather than SMTP itself. Similarly, while email encryption is an important aspect of secure communications, it is handled by different protocols and technologies. Lastly, retrieving email from remote servers is not within the purview of SMTP, as that function is fulfilled by protocols designed specifically for email retrieval.