NET.exe

The NET Command is used to send network messages as follows:

Network broadcast messages use "messaging names". A messaging name can be the ComputerName, your UserName or any other name you add as part of the NET NAME command line.

To add an additional messaging name for receiving messages.
NET NAME extraname /ADD

To remove a messaging name
NET NAME extraname /DELETE
It is not possible to remove the ComputerName with this command

To send a broadcast message to another user
NET SEND j_smith Meeting changed to 3 p.m

To send a broadcast message to another machine
NET SEND mc_144 Meeting changed to 3 p.m

To send a message to all users who have a session with the server
NET SEND /USERS This server will shut down in 5 minutes.

To send a broadcast message to the whole domain
NET SEND * This server will shut down in 5 minutes.

To send a broadcast message to another domain
NET SEND /DOMAIN[:other domainname] This server will shut down in 5 minutes.

To use NET SEND the Messenger service must be running

Related commands:

NET - Manage network resources
MAPISEND - Send email from the command line
Q330904 - Messenger Service Spam