So who do we see addressed on this email?
It's a mix of people from the reelection campaign and senior White House staffers. The purpose of this email was to craft a political message with the disposition of making the administration look better, or at least not any worse, because of this event.
Since when are senior government officials in the White House allowed to engage in election politics? It's been observed that this is a felony, in violation of The Hatch Act, as no government officials, beside the president and vice president, are allowed to engage in election politicking, and this email clearly demonstrates that they are.