What do you mean by sending a read reply?

the option "send read receipt" in imessage means to let you know whether the other party has read the information.

settings for the read receipt of p>iPhone SMS:

1. enter "settings".

2. enter "information" under settings.

3. turn on or off the "send read receipt" switch as needed.

4. If the option of sending a read receipt is turned on, then when the other party receives the message or does not close the chat window, the small words that have been read will be displayed below the message of the sender's chat window.