SMTP or Simple Mail Transfer Protocol is a TCP/IP protocol used to send and receive email. The protocol facilitates message transfer between mail servers.
Key Points
- The majority of email systems use SMTP to send messages from one server to another. Messages are subsequently retrieved using email clients through protocols like IMAP or POP3.
- SMTP serves a dual purpose — it delivers email from a mail client to a mail server
- SMTP uses ports 25 or 587 as some ISPs will block port 25