SMTP stands for Simple Mail Transfer Protocol, which is an Internet standard communication protocol for electronic mail transmission. SMTP is used to send, receive, and relay outgoing email between senders and receivers. It is a TCP/IP protocol used in sending and receiving email. SMTP is a connection-oriented, text-based protocol in which a mail sender communicates with a mail receiver by issuing command strings and supplying necessary data over a reliable ordered data stream channel, typically a Transmission Control Protocol (TCP) connection. SMTP is used most commonly by email clients.

SMTP is not used to receive messages; IMAP and POP are used instead. SMTP servers are used by mail servers and other message transfer agents to send, receive, and relay mail messages. SMTP determines which servers will receive your relay messages. SMTPS (Simple Mail Transfer Protocol Secure) is a method for securing the SMTP using transport layer security.

In summary, SMTP is a protocol that allows you to send and receive emails. It is used by mail servers and other message transfer agents to send, receive, and relay mail messages. SMTP is not used to receive messages; IMAP and POP are used instead.