I want to line the text messaging system. If we change your mind, press the other end has not yet been read, you can delete a message by the other parties never seen.
Line with that message out. If you change your mind Then the other party has not pressed readers. You can delete the messages without the other person never sees.
Want line system that sends out a message. If we change. Then the other party didn't press the reading. It can remove the message out without the other never see.