If it's a personal email to the Wikipedia Foundation, or to our lawyers or something, then that's a different matter. The problem is that the Wikimedia Foundation aren't the ones putting the facts in the articles. It's if User:RandomName puts in a new date of birth and cites at the bottom "Personal Correspondence". There's no way we can check if that's true, and there's no one to turn to if the article's subject starts demanding corrections and accountability.
Definitely. Sorry, I was referring to the case where someone does contact the foundation, but has no published bio to refer to. Someone recently (here? On a talk page?) gave the example of themselves, where their DoB on WP was incorrect, but they couldn't find a published source to back them up. According to the guidelines, they had no right to remove it. If we accept personal correspondance to the foundation as a verifiable source, then a simple email would suffice.
Steve