NetSend for Windows NT Description:

NetSend for Windows NT is a
Graphical WinPopup-like messenger utility, similar to Microsoft's WinPopup
utility, but it's designed for Microsoft Windows NT(TM). This handy utility
lets you send popup messages to other Windows NT PC's on your network that
are running the Messenger Service, and to Windows 95 PC's that have
Microsoft WinPopup running. The Full Registered Version allows you to Send
'Unlimited' Length Messages, the ability to Send Messages to Entire Domains
and Workgroups that are defined on your network, and NEW to v.3.0.0, the
ability to Send Messages to All Users that are connected to the PC or Server
running the NetSend for Windows NT software.