POP stands for Post Office Protocol. It is one of the protocols used to check non-web-based Email accounts (the other being IMAP).

You may want to access your POP3 mailbox via telnet at times… So here is a quick and dirty guide to doing so..

Telnet into your POP3 account on port 110 (the standard port for POP3 – change if you have a non-standard installation):
telnet <mail.server.com> 110

You will receive some sort of welcome message normally starting:
+OK

Now we need to login:
USER <username>

The server will reply with something like:
+OK User name accepted, password please

Enter our password:
PASS <password>

The server will reply with either a:
-ERR <Error Message>
or
+OK <Welcome Message>

LIST will output a list of message ID’s and their sizes.
RETR <Message #> will retrive an individual message.
DELE <Message #> will delete an individual message.

Type QUIT to finish your session.

NOTE: A “lock file” is created when you log in and is deleted when you log out, and whenever someone tries to log in the server allows them access only if the lock file does not exist (which means that there’s nobody currently logged in).