Email Protocol used for retrieving mails from a mail Server.
The email is retrieved from the server by downloading it to one device and deleting it on the server. This is contrary to IMAP where mails are kept on the server and synchronised to the client.
By default POP3 use port 110 and when using SSL/TLS port 995.
Commands
Communication is done with text-based commands in ASCII format:
USER <username>: identifies the user.PASS <password>: authentication of the user using its password.STAT:requests the number of saved emails from the server.LIST:requests from the server the number and size of all emails.RETR <id>: requests the server to deliver the requested email by ID.DELE <id>: requests the server to delete the requested email by ID.CAPA:requests the server to display the server capabilities.RSET:requests the server to reset the transmitted information.QUIT:closes the connection with the pop3 server.