The message stays in your Outbox (and the recipeint's Inbox) until the recipient opens his Inbox, at which point it moves from your Inbox to your Sentbox. Clear as mud! The recipient does not have to open the message itself, just opening his Inbox will show it as being received. Now we did add the text of the message in the notification e-mail, and some people are seeing it there and not opening their Inbox, if it does not require a reply. That way it stays in your Outbox.
Chris
"Je n'ai pas besoin de cette hypothèse." Pierre-Simon de Laplace