There's a reason this works that I haven't seen discussed much. Namely that because of archiving rules (these are historical documents from elected+appointed of

There's a reason this works that I haven't seen discussed much. Namely that because of archiving rules (these are historical documents from elected+appointed officials) and the propensity for emails to be subpoenaed in investigations that much of the "work" of elected officials has been pushed off to private email services. While it's tempting to think this happens for nefarious reasons, I suspect that it's mostly for the same reason that security is routinely circumvented in non-governmental organizations: it's cumbersome. So it's not wildly unexpected that you might get an email from a senior White House staffer from a non-official address.