What does it mean when an iMessage doesn't say "Delivered" nor "Not Delivered"? I sent an iMessage to a friend, and at the bottom it doesn't say "Delivered" as it usually does. It doesn't say "Not Delivered" either, it just doesn't say anything at all.

What does it mean when an iMessage doesn't say "Delivered" nor "Not Delivered"?
The receiving device is probably off, in sleep mode, out of cell reception, flat battery - something like that.