Which protocol is used to send email over the Internet?

The protocol used to send email over the Internet is SMTP (Simple Mail Transfer Protocol). It is specifically designed for sending emails from a client to a mail server or between mail servers. FTP (File Transfer Protocol) is used for transferring files between computers, not for email. HTTP (Hypertext Transfer Protocol) is used for loading web pages on the Internet. Therefore, neither FTP nor HTTP is used for sending emails. SMTP is the standard protocol for email transmission, making it the correct choice.