The server didn’t need to be hacked if she sold access to it.
Could check timing of donations to the Clinton Foundation for clues.
It did if she wanted at least quasi-plausible deniability. Like telling some thief the location and type of safe for the house so you can get the insurance money for covered items. The difference here would be the thief actually paying or ‘donating openly’ to a fungible charity you run for the info about the safe.
Freegards