A ‘read receipt’ feature is present in the iOS Messages app and enabled by default. This allows the sender to see if and when the recipient has read the message. If you don’t want the feature at all you can get rid of it by toggling off the ‘Send Read Receipt’ option in your iPhone’s Settings app under the Messages section.
Read receipts can be useful, but not all the time and certainly not for all your contacts. If you own an iPhone 6s or 6s Plus you can use the ‘peek and pop’ capability provided by 3D Touch to view a message without sending a ‘read receipt’ and with no need to completely disable the feature. Here’s how you can do it:
Open the Messages app (but do not open the message thread you want to read).
Force press on the main screen of the Messages app (where you can see all the message threads) to enable the ‘peek’ 3D Touch feature. Then you can read the new iMessage without sending a read receipt as long as you continue to 3D Touch the summary screen in the Messages app.
You can press a bit harder on the screen to ‘pop’ the message although be aware this will send a ‘read receipt’ immediately. Alternatively, you can swipe up while the ‘peek’ screen is still active to open up the 3D Touch options and mark the iMessage as read, send on of your preset replies or jump right into the conversation to create a custom one.
Right now, there is no way to enable the ‘Read Receipt’ feature only for specific contacts, so the 3D Touch method can certainly come in handy, at least occasionally. Those with older iPhones which are not equipped with 3D Touch-enabled screens can open the notifications and see the first lines of a message without sending a ‘read receipt. Nevertheless, this method doesn’t allow you to read the whole message but at least you can see if it’s important and needs an urgent reply or it can be postponed.