Thank you for the reply. Can I ask if it's a carrier requirement why other phone don't have the pop up on their stock messaging apps like Samsung does?
Searched for this online and set up an account just to say that we agree with @Keelar. This is the only phone where we've seen this happening so it must be that other phones are handling this notification differently.
Assuming that the notification is required, it should not need to be a speed bump when reading messages.
Also: this only seems to be affecting people with Samsung phones.
