They will never know.. Unless you don't respond to something they post..
If you only change your email on your existing Facebook account, you will still be blocked. If you make a whole new Facebook account you won't be blocked.. Until you request him as a friend and he realizes it's you, and blocks you again..
Apparently this is normal on Facebook because the same thing happens to me. I think you will only see their posts in your newsfeed IF their posts are public - meaning you could have gone to their page at any time and seen them.
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