I've done that before - it's pretty easy. Only problem is that now a lot of people have that service turned off.

>You could use the Windows NET SEND command for this.
>
>http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/net_send.mspx?mfr=true
>http://en.wikipedia.org/wiki/Messenger_Service
>
>>I have a client that would like a "Station to Station Messaging"
>>system. Their are about 10 stations on the Local Area Network.
>>He would like an application that would allow one station to
>>send a message to another station. A popup window would open
>>when a station received a message showing who the message was
>>from and the level of urgency. He would like these messages
>>to be logged into a database.
>>
>>Do you know where we can get an application like this?
>>
>>Thanks,
>>Terry Harris