The delivery report for SMS messages is a convenient feature provided to you by the mobile operator. The delivery report tells you whether an SMS message was successfully delivered to the recipient.
This does not mean that the SMS has been read, but you can be sure that the recipient has received the SMS on the smartphone. The delivery report is sent as info, which can also be viewed via the details of the SMS.
If you want to receive such a delivery report for sent SMS on the Samsung Galaxy M31, M21, M30S and M20, you have to activate the corresponding option "Show when received".
We will now explain how this works with the SMS delivery report on the Samsung Galaxy M31, M21, M30S and M20:
Enable SMS delivery reports on the Samsung Galaxy M31, M21, M30S and M20 - Instructions
1. opens the SMS messages app.
Now tap the three-point symbol in the upper right corner and continue with Settings.
3. in the message settings select "More settings" and then SMS
As a first option you can now change the slider at "Display when receiving" from "Off" to "On".
You have now activated delivery reports on the Samsung Galaxy M31, M21, M30S and M20. Now when you send an SMS message and it is received on the recipient's device, you will receive a message about it on your Samsung Galaxy M31, M21, M30S and M20.