Personally I think read receipts on their own per message are not a bad idea but I do agree that there shouldn't be an incentive for recipients to game the syst

Personally I think read receipts on their own per message are not a bad idea but I do agree that there shouldn't be an incentive for recipients to game the system by falsely marking messages as read. It should be optional. Not all messages need to have receipts. Maybe you should charge for that as well?