>A Broadcast Message is sent now to all signed on users of the applications. It is not stored for later retrieval. So any current user of the application would get the message. Something like "The XXXXX application is coming down in 10 minutes for maintenance.". I do not want someone who signs on after the broadcast to receive the message.

Since you know when the message is created who is logged into the VFP application, only create the message for those users.