Which protocol is primarily responsible for sending emails?

The protocol primarily responsible for sending emails is Simple Mail Transfer Protocol (SMTP). SMTP is designed specifically for sending and routing emails from the sender to the recipient's email server. It establishes how email messages are transmitted across the Internet and is an essential component of the email communication process.

In the context of email systems, SMTP is used when you send an email from your email client (like Outlook or Gmail) to an email server. It handles the dispatch and forwarding of the emails to the right addresses. This makes it the backbone of email sending operations.

In contrast, while other protocols such as POP3 (Post Office Protocol version 3) and IMAP (Internet Message Access Protocol) are used for receiving and retrieving emails from the mail server, they do not play a role in the sending of messages. Similarly, HTTP (Hypertext Transfer Protocol) is used for transferring hypertext files, mainly for web pages, and is not involved in email transmission. Therefore, SMTP is distinctly recognized as the protocol that facilitates the sending of emails.