I would like to send message to targeted receivers.
I need to warn my users with LAN messages in case of breakdown of applications, and not mails because nobody read them!
Was looking around and found this program: Winsentmessenger
It takes a bit of work to get setup, but it should work on all versions of windows. That being said, I would still recommend that you use OS provided services like "net send" or "msg" depending on your OS.
You can't find net send under Windows 7 because it disappeared. but you can use software as desk alerts with dmessage to send lan message.