Which SMTP command would you use to terminate a mail session?

The command used to terminate a mail session in the Simple Mail Transfer Protocol (SMTP) is QUIT. This command is designed explicitly for ending the connection between a client and a server. When the client sends the QUIT command, the server processes the request, finishing any ongoing transaction and closing the communication channel properly.

Using the QUIT command is essential for maintaining the integrity of the session and ensuring that resources are released on the server side. This orderly shutdown prevents issues such as resource leakage or session hanging, which can occur if a session is terminated unexpectedly or improperly.

In contrast, the other commands listed serve different functions within the SMTP protocol. For instance, DATA is used to send the body of the email message, MAIL FROM specifies the sender’s email address, and RCPT TO identifies the recipient of the message. None of these commands is intended for terminating a session; they perform distinct tasks related to the sending of an email.