There is a hillaryclinton.com domain. Currently, it's screeching "We can't risk a Donald Trump presidency."
It belongs to Hillary for America. Its creation date was 2005-04-21T05:37:37Z. That's 1:37:37 am, New York time. Somebody was burning the midnight oil.
She had already been a senator since 2001.
Now why would Huma use that email address? Maybe it was for convenience.