Introduction to the POP3 command

What is POP3

POP3 (Post Office Protocol 3), the 3rd version of the Post Office agreement, provides a way to connect personal computers to the Internet's mail server and electronic protocols for downloading e-mail. It is the first offline protocol standard for Internet e-mail, POP3 allows users to store messages from a server on a local host (that is, their own computer) while deleting messages that are saved on the mail server, and the POP3 server follows the POP3 protocol's receiving mail server to receive e-mail.

POP3 command

POP3 commands include:

User Username authenticated username

Pass Password Authentication password authentication, the authentication passes the state conversion

APOP Name,digest approves a secure transmission of passwords, which results in state transitions, see RFC 1321.

STAT Processing Request server loopback mailbox statistics, such as number of messages, total bytes of mail

UIDL N Processing server returns the unique identity used for the specified message, and returns all if not specified.

LIST N Processing server returns the size of the specified message

RETR N handles all the text of a message returned by the server

DELE N handles the server tag deletion, QUIT the command is not actually deleted when executed

RSET handle undo All DELE Commands

Top N,M processing Returns the first m line of n Mail, M must be a natural number

NOOP processing server returns a positive response

QUIT wants to end the session. If the server is in the process state, now go to the update status and delete the messages that are marked for deletion. If the server is in an "approved" state, the server does not enter the update state when the session ends.