Iphone trying to send iMessages to non iphone users - HELP!

My friend just switched from Verizon to Sprint. He has NEVER had an iphone. He currently has some type of galaxy or android. As of last night all of my texts to him are being sent as iMessages (which he obviously doesn't receive). He's had the phone for two weeks and up until yesterday we were able to text via SMS with no issues. I still get his texts - he gets nothing from me and it only shows on my phone as going through as an iMessage. I've tried deleting his contact and adding it again. It still shows up blue in my contacts as if it's an iphone (which it obviously is not). I know I can turn off my iMessage on my phone but I like using it because the majority of my friends and family have iPhones. Is there any way to fix this??