The steps of an SMTP transaction involve the following sequence: the client connects to the SMTP server, the client sends a HELO or EHLO command to identify itself, the server responds with a greeting message, the client sends the MAIL FROM command to specify the sender’s email address, the server acknowledges this, the client sends the RCPT TO command to specify the recipient’s email address, the server acknowledges this, the client sends the DATA command, the server responds indicating readiness to receive the message content, the client sends the email message followed by a period on a line by itself to indicate the end of the message, and the server responds to confirm receipt of the message. Finally, the client sends the QUIT command to close the connection, and the server acknowledges and closes the connection.
SMTP works step by step as follows: The email client establishes a TCP connection to the SMTP server on port 25. The client sends a HELO or EHLO command to the server to initiate the conversation and identify itself. The server responds with a 220 service ready message. The client issues a MAIL FROM command to specify the sender’s email address, and the server responds with a 250 OK message. The client sends an RCPT TO command to specify the recipient’s email address, and the server again responds with a 250 OK message. The client sends the DATA command, and the server responds with a 354 Start mail input message. The client sends the email content followed by a single period on a line to end the data section, and the server responds with a 250 OK message indicating successful receipt. The client sends the QUIT command to end the session, and the server responds with a 221 Bye message, closing the connection.
The first step in the SMTP process is the initiation of a connection between the email client and the SMTP server, typically over port 25. This is followed by the client sending a HELO or EHLO command to the server, which identifies the client to the server and begins the SMTP conversation.
The phases of transfer in SMTP include the connection setup phase, the mail transaction phase, and the connection termination phase. In the connection setup phase, the client establishes a TCP connection to the server and identifies itself with a HELO or EHLO command. In the mail transaction phase, the client sends the MAIL FROM, RCPT TO, and DATA commands to transfer the email message. In the connection termination phase, the client sends the QUIT command to end the session, and the server closes the connection.
The sequence of the SMTP protocol is as follows: the client connects to the server and sends a HELO or EHLO command, the server responds with a greeting, the client sends the MAIL FROM command to specify the sender’s address, the server acknowledges this, the client sends the RCPT TO command to specify the recipient’s address, the server acknowledges this, the client sends the DATA command to initiate the transfer of the message content, the server responds with a readiness message, the client sends the email content ending with a single period on a line, the server confirms receipt of the message, and the client sends the QUIT command to terminate the connection, which the server acknowledges by closing the connection.