It says it's an iMessage but the person doesn't have an iPhone?

So whenever I go to text this person it says it's an iMessage, but he doesn't have an iPhone. He used to, but he got a new phone however it still says iMessage so I'm just worried because what if he's not getting the messages.

Added (1). Yes of course I'm irritating him. When did I ever say I kept texting him, all I said I was afraid if I were to send a message that he wouldn't get it.

Your irritating him. He's getting all the messages but obviously doesn't want to reply to you leave him alone. Find someone new to talk to

I don't think he is getting the messages.