Eric Sink writes a great article called This Blog Entry is Urgent and it includes:
When I see an envelope that says, (Do not discard this envelope(, I know immediately that it will be safe for me to throw it away unopened.
When I see an envelope that says (Special Offer(, I know with certainty that the offer contained therein is not special, and was in fact distributed to everybody with a pulse.
When I see an envelope telling me that Ive won, I see a completely unambiguous message. There could be no clearer way to communicate to me that I have in fact not won anything at all.