If the user reads the message using the Reading Pane, then the Read Reciept does not get generated. However, when the user deletes the message, the deleted without reading message will be genereated.
As a rule, Read / Delivery Reciepts do not guarantee anything about the actual reciept of the message. A Delivery Reciept will be generated once the message hits the server, not the actual individual.
Dawn Bleuel
Word MVP
