How to block an imessage user?

(First time asking a question on this, so please pardon me if i sound stupid.) So, on "imessage" for my iphone 4, i used to have this person in my contact list, but he lately has been spam texting me and will not stop, and i know him, but we aren't really friends, so i just deleted his contact. The problem is, he won't delete mine from his ipod, so he can still text me and continues to spam me. I have already gone into "settings," "notifications," "imessages," and set it to "my contacts only," but that only makes it so the message does not pop up when he texts, is there any way to completely block him from being able to text my imessage without jailbreaking my phone? Any help is appreciated, thank you.

If he harassing you, you may actually notify Apple and they handle him from there.