Following her devastating 2008 defeat, Hillary Clinton suspected her loss was not a result of her own shortcomings, but rather the fault lay with her staff. In order to prove this to herself, she conducted a review of the email correspondence generated by her campaign staff in 2008.
From Shattered: Inside Hillary Clinton’s Doomed Campaign (emphasis added)
In the summer of 2008, years before her private e-mail server became a campaign issue, Hillary learned about the power of digital snooping. At the time, she was conducting an autopsy of her failed bid against Barack Obama, and she wanted an honest accounting of what had gone wrong. So she instructed a trusted aide to access the campaign’s server and download the messages sent and received by top staffers.
She believed her campaign had failed her – not the other way around – and she wanted “to see who was talking to who, who was leaking to who,” said a source familiar with the operation.
In an interesting twist, it seems that Hillary’s snooping through the emails of her staffers, may have influenced her decision to conduct her official State Department business on a private server. More from Shattered (emphasis added)
After years of watching adversaries comb through her public records for any hint of a scandal, and after accessing her own aides’ e-mails, Hillary well understood the danger of exposing her own private thoughts to scrutiny. And that was reason enough to want them shielded from political enemies, journalists, and the public.
This revelation should give pause to all who are still operating under impression that the Chappaqua server was just an innocent oversight. It’s pretty clear that Hillary knew damn well what she was doing when she decided to install and use a private server. It was a security measure. Not to protect state secrets mind you, but rather to protect Hillary’s actions while Secretary of State from public scrutiny.