Running a mail infrastructure properly is a complex problem. I would not recommend it for most people. There's a reason most companies outsource it these days.
So are those of us who have done infosec with TS/SCI clearances, and have a deep understanding of how it's supposed to work vs how easily it was all circumvented.
Wonder if they have a NAC and if those who manage it would kill all packets to and from that server. Surely the government has some infosec professionals who will uphold their oaths and do their jobs.
It also had the signs of a phishing test. You'd be in trouble responding to those, too, even just to say fuck off.