This program allows you to send messages from the client xMessenger to a remote computer on which the server xMessenger was launched. Just know the IP address of the remote machine and make sure that TCP port 11,112 is available to open message windows or show the tooltip in the notification area of the target computer.
You can customize the error messages, icons, and allow the user to answer. To avoid too many messages, one customer at a time can connect to the server and send messages.
The program source code is available under the GPL.