Set Delivery Setting send email 500 But send 71 email

@developer - You can set 1M in a minute, that doesn't mean it will actually send that much. The idea is that number is a maximum, only if possible.
Please take into consideration the latency between your server and EE, this plays a very important role.
if you want to see how things go internally, debug the send campaigns command and you'll see exactly how long it takes to deliver an email.