> and each hop in the network has a positive acknowledgment that the message has been committed to stable storage If that were true there wouldn't be silent dr

> and each hop in the network has a positive acknowledgment that the message has been committed to stable storage If that were true there wouldn't be silent drops in the last mile. > In general, I think whatever you are suggesting will not have all the same guarantees of delivery as email. ACK is not to guarantee that messages are delivered though. It's a mechanism that ultimately would let the sender know the message was most likely not delivered.