POP pseudo code protocol
establish connection
C: Hello, I would like to start a POP session.
S: OK, I am a POP server running at xxx.xxx.xxx.
C: I am Outlook Express running at yyy.yyy.yyy.
Loop until a valid user name is entered:
S: What is your user name?
C: I am user xxx.
S: If invalid name, send error message.
End of loop
Loop until the correct password is entered:
S: What is your password?
C: My password is xxx.
S: If incorrect password, send error message.
End of loop
S: You have xxx new messages.
S: Would you like to see headers only or the entire messages?
C: Reply "headers" or "messages."
If reply is "headers"
S: Send headers
Otherwise
S: Send messages
End if
C: I got them, Goodbye.
S: Goodbye.
end connection