from a win9x you can send messages using the mailslots. The name of the mailslot that Winpopup used is "messngr" you have to write a string to the mailslot that is being monitored by winpopup or NT messenger service. The string contains 3 null characters that separate the sender name, recipient name, and body of the message. It MUST be in that format for the messenger service to translate it correctly. I you need more more info or have discovered any more tricks (like sending messages to a user name) please e-mail me.