SMTP (Simple Mail Transfer Protocol) is part of the Application Layer of the TCP/IP protocol. TCP/IP protocol used in sending and receiving e-mail. An SMTP server is an application that’s primary purpose is to send, receive, and relay outgoing mail between email senders and receivers. It works with Message Transfer Agent(MTA), to send mail at the correct email address.
This Protocol is used to manage the SMTP (Simple Mail Transfer Protocol) is limited in its ability to keep the messages at the receiving end, it requires some other protocols that let the user save the messages in a server mailbox and let them download periodically from the server, and those protocols are :
s soon as it listens for a TCP connection from any client, the Simple Mail Transfer Protocol process initiates a connection on that port. After successfully establishing the TCP connection the client process sends the mail instantly. The SMTP server is the always-on listening mode. A
SMTP is an application layer protocol. If a person wants to send the mails to open the TCP connection to the Simple Mail Transfer Protocol server and sends the mail.
It is an Internet Standard for sending emails on the internet.
The sender prepares the mail and delivers it to the recipient’s mail address. Here, the MTA(Mail Transfer Agent) transfers this mail across the internet.