Receiving email: POP3 (Post Office Protocol v3)

An email client sends its messages by relying on SMTP and retrieves them using POP3. SMTP is similar to handing your envelope to the post office, and POP3 is similar to checking your local mailbox

Some common POP3 commands are:

• USER <username> identifies the user

• PASS <password> provides the user’s password

• STAT requests the number of messages and total size

• LIST lists all messages and their sizes

• RETR <message_number> retrieves the specified message

• DELE <message_number> marks a message for deletion

• QUIT ends the POP3 session applying changes, such as deletions

If anyone was to capture the network packets they'd be able to get the username and password as it isn't encrypted