I occasionally get abusive messages on xbox, if my opponent deems that I have had a lucky win on Fifa for instance. I tend to just block them, but does the other user know that I have blocked them, or do they merrily live their lives without knowing this devastating option has been unleashed on them?
The person you have blocked has no idea that they are blocked. They can still send you a message/invite but you will never receive it. The original sender gets no message or indication that they are blocked.