Which protocol is often used for sending emails?

The Simple Mail Transfer Protocol (SMTP) is the correct answer because it is specifically designed for sending emails across the internet. SMTP operates over a client-server model where the sending client communicates with the mail server to transfer emails to the recipient's server. This protocol handles the sending of messages, enabling mail transfer between different email servers, ensuring that emails are dispatched properly and efficiently.

While other protocols are related to email, such as IMAP, which is used for retrieving and managing messages from a mail server, SMTP's primary role focuses on the outgoing transmission of email. Therefore, it is indispensable in the email delivery process. SNMP, on the other hand, is focused on network management and monitoring, while HTTP is primarily used for transferring web pages and resources on the internet, not for handling emails.