Not sure about that. I send messages all the time to standard Verizon cell phones that have no option for delivery receipts (I know for a fact a few I send to do not have that option on their phone, I had one before I switched to the BB), and I receive the Check Mark and the little D. Had some problem after updating to .61, but I found that I had to have the following setup and now it works again.
Options>SMS Text>Delivery Report 'ON'
Options>MMS>Notifications>Allow Delivery and Confirm Delivery 'CHECKED'
Under EMAIL Messages>Email Setting>I have 'Confirm Delivery' and 'Confirm Read' both set to NO. (I had them set to yes, and I was receiving receipts for all my emails.
Possibly, the check and little D don't appear if the person you are sending the message to are out of the standard Verizon network and on an extended network? I really don't know for sure.
Greetings from the Colorado 'High Desert' Plateau; Canyon Country, Utah