If you want to send the message to all the connected users through the Broadcast Message option in server pane of Domino Administrator, then add the "(!)" Exclamation mark with out inverted commas but with brackets. This will bring up the pop box on the user's screen. Unless and until a user does not press OK, he or she won't be able to work on Notes. If you don't add (!) before the message, the message will appear at the bottom of the screen, which will not interrupt their work and it's hardly visible. By using this, your users will not be able to complain that they didn't see the message.