Iphone SMS has always been able to show that the other party has delivered and read it, but yesterday I started sending messages to the other party. What text does it become below?

Try this problem with two Apple phones.

Under normal circumstances, Apple has the function of receiving short messages.

This function requires the other party's Apple device, and the other party has opened the read receipt.

In Settings-Info-Open Read Receipt. As long as the other party opens it, you can see whether the other party has read it.

Similarly, if the other party does not turn on this function, there is no way to see it, only to see whether the information has been sent to the other party's mobile phone.