Can I use iOS 7 blocking to block iMessages between Apple IDs instead of phone numbers? I have iOS 7, which provides the ability to block calls and messages. Can I block someone texting me on iMessage from their Apple ID to my Apple ID? …or can I only block based on phone numbers (not Apple IDs)?
Yes, on iOS 7, you can block someone from sending you an iMessage from their Apple ID. When you block a contact from sending you texts, it applies to SMS (sent to phone number) and iMessage (sent to phone/Apple ID email). Currently this works only on iOS devices. Any iMessages received on a Mac are not blocked.

How it works is described in detail here - Silence is Golden: A Guide to Blocking Calls and Texts in iOS 7


  What about texts?
  
  If you’re sending a text, it will look like it was delivered. If you’re sending a message to someone who has blocked you, and you’re using iMessage, it will say “delivered” — exactly like a text that went through.