howto make a message show up only once. (like system messages)

I am trying to show a message only once after a certain event (using rules to create a message and a views block to display it. But it keeps showing in a views block all the time.

I followed the documentation and http://www.webwash.net/tutorials/log-site-activity-message-and-rules basically.
Works fine. But the message keeps popping up. Is there some way to prevent this. In the view? Using rules?

Rules doesn't seem to work #2291695: Messages aren't marked as viewed