Is there a way to block messages in your "other" inbox on facebook?

I made a new FB account at the end of last year, I rarely use it but when I saw that there are 2 inboxes, I had a few messages off some people and deleted them. However, one guy wouldn't stop messaging me so I replied and told him to leave me alone. He carried on so I blocked him. He then made a new account and started messaging me again and I told him to f**k off because he was really being so creepy and weird. This morning I've seen he made ANOTHER account and sent me some really disgusting, explicit messages and has really tried to insult me too. I'm annoyed that he can keep doing this, my profile is completely private so nobody can see anything, nobody can search me either so he must have saved the url of my account or something. I've reported the messaged to FB but is there a way of blocking messages that go into the "other" inbox completely? Or stop messages from non-friends completely? Please let me know if there is, thanks guys