This is sort of an amazing exchange.
Here’s the thing. She didn’t just use a non-government email address, like Gmail or Yahoo, or her ISP. She set up her own domain and server (though the server may be shared, that’s still unclear to me). That means that she has total control over what data is preserved, and what can be destroyed. Now, in theory, people received her emails, and people sent her emails, so multiple copies exist, even if she purges the server. But if Huma had an address on the same domain, then her emails could be wiped as well. And there’s no explanation of why she did this. But it sure as hell looks like a way to avoid a FOIA, or subpoena. Which is classic Clinton.