I have the Note 9. He has the S9+. My daughter has the S9 and it doesnt do it with hers. We have the same carrier. And its the messaging app thats default, i assume. We both turned it (the read/delivered) on just to see what it was about and sent a message to him and he replied (the S9+) and said cool and shut it off. But now it is still doing it. I didnt change anything else. Literally turned it on and sent a message, he replied and we went back and we shut those settings back off. It wasnt doing it before, until I tried it. So i dont think its the carrier standard. Not trying to be petty but I dont like when people can see when I read their messages lol. I like to ignore people sometimes haha. But as far as I know, its only doing it between his S9+ and my Note 9. Ugh....did it automatically change our messaging app when we turned it on by chance? Thats all I can think of. Thank you!