Responses
It prevents them from posting on your Message Board, DM'ing you, or replying to your Answers to Questions. I think it might also prevent them from replying to your Topics on manga titles? Not sure, though.
It doesn't stop them from Answering your Questions, or replying to other people's posts on your Message Board or replies to your Questions, and I think they can still reply to your Experiences but I couldn't tell you if that's true or not.
Sorry I keep coming on your message board so often, but what does blocking a person do? Can they still respond to you?
(I'm asking you specifically, since I'm sure you've blocked many people)