Which protocol is primarily used for sending emails?

The protocol primarily used for sending emails is SMTP, which stands for Simple Mail Transfer Protocol. SMTP is designed specifically for transferring messages between servers and sending emails from email clients to servers. When you compose an email and press send, SMTP facilitates the communication necessary to deliver that email to the intended recipient's mail server.

While FTP (File Transfer Protocol) is used for transferring files, and HTTPS (Hypertext Transfer Protocol Secure) secures the transmission of web data, neither are suited for email transmission. TCP/IP, which stands for Transmission Control Protocol/Internet Protocol, is a fundamental suite of protocols for communication over the internet, but it does not specifically handle the sending of emails. Instead, it provides the underlying networking framework that protocols like SMTP utilize to send emails effectively over the internet.