Deleting apple imessages So I did this thing. I sent this imessage and but the guy on the other end didnt have wifi I guess. It didnt say "sending" at the top and it didnt say delivered. So I turned on Airplane Mode, sent the imsg as a text and after it failed to deliver I held down on it, selected more then clicked delete. And now I'm paranoid and wondering whether or not he actually got the text. Can anyone help?
Once you send an iMessage, if it is completely sent, it will be held indefinitely by Apple (not sure how long indefinitely is) until it is received by the other party. There are occasions where you won't get a "received" notice - if, for example, they have receipts turned off, or if they went out of range after receiving the message (happens on the subway here in NYC, where there is cell service for 300 feet, then nothing until the next station). Even then, it will sometimes send a receipt when it reconnects, but it's not perfect. 

With SMS, it seems to vary by carrier. I've had messages that I know were sent but never received, and there aren't receive receipts for SMS. So YMMV with SMS.

The only time you really know 100% for sure is when you get the received receipt from iMessage. I'm not sure if this helps with your worries.