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PHP: “Notice: Undefined variable”, “Notice: Undefined index”, and “Notice: Undefined offset”
Well, for starters you're assigning $realFirstName and $realSecondName, but you're using your regex with a variable called $realName which i can't see anywhere else in your code.
You have the same issue when checking $body, as $_POST['body'] isn't anywhere in your form.
Your script gives a lot of undefined variable errors for the same reason.