What does the SMTP command DATA do?

The SMTP command DATA is crucial in the process of sending an email as it designates the start of the email message body. When a mail server receives the DATA command, it understands that the following data will consist of the body of the email, including the headers and the message content itself.

This command is typically issued after establishing a connection and providing the necessary sender and recipient information through previous SMTP commands. Once the server acknowledges the DATA command with a confirmation response, the sender can submit the body of the email. Following the message body, the sender must end the data input with a single period on a line by itself, signaling that the message has been completely sent.

Understanding this function is important because it highlights the structure of an email transaction and how SMTP facilitates communication between mail servers, ensuring that the body of the email is correctly transmitted and recognized as such.