So I randomly searched up a name and he was my former friend from about a few years ago. He moved away and I graduated high school, but just about a week ago I searched his name but he didn't show any image.I clicked the Message button without sending him a Friend Request but I never heard a reply. I didn't even see a Seen at x:xx time under my message I sent him. Does this mean he received it or not? I'm pretty sure somebody this popular like him would go on Facebook all time.Oh and another similar case occurred with messaging. I made a new friend at my University in one of my classes and he told me to add him on Facebook. Then he told me to message him. So he went on his phone about 30 minutes later but he didn't receive the message. However, it showed up on my Sent box. How is that possible? 
Sending messages to non friends on Facebook?
facebook;facebook messages
Your message might have ended up in his spam folder: https://www.facebook.com/messages/other/ . This happens sometimes if you aren't Facebook friends.