I was sending messages to my friend through my iPhone, it showed that it was "delivered" each time, and then out of nowhere I sent a few more and it showed nothing? I can't tell whether the remaining few messages were sent or not. Does that mean I was blocked? Is there a problem with the cellular data on my end or on my friend's end? Was my friend's phone not on? What could it be and how can I tell?
Read more: https://iphoneus.org/faq/what-happens-when-you-send-an-imessage-to-someone-who.html