How to stop galaxy text read receipt
I've got my message read turned off & my friends galaxy still knows when I've opened his message
Turning on or off message read receipts only affects iMessages. Therefore, it has nothing to do with what's happening between you and someone who has a non-Apple phone. Therefore, either one or both of your carriers provides such a feature for SMS. This feature is can be enable by third party messaging apps on Androids. There's nothing you can do about that.