How does it work? MacXPop is merely an application that handles incoming messages to the smb daemon. The Mac OS X smb daemon already has the ability to receive "net send" messages. However, there is no built in "WinPopup" equivalent to display these messages. That's where MacXPop comes in. It does not run as a daemon, but rather is a simple application that the smb daemon launches only to display a message on the screen, then ends.