Our FBI director James Comey recommends no charges for Hillary Clinton after she sent thousands of classified emails on a unsecure email account. She has had a private server set up at her house, also during her years in office. "Though her work-related emails were government records, she didn't turn over copies until more than 30 lawsuits were filed. Before providing her correspondence, Clinton and her lawyers witheld and subsequently deleted tens of thousands of messages that she claimed were pesonal, and not classified on multiple occasions." 
The FBI recovered some of those deleted emails, and found classified emails. Among them were about a dozen top secret documents, which should never have been sent on a hackable email and server. This issue was thought to be a major obstacle for her campaign, but it seems like it's gone for now. The DOJ sure won't press charges, Clinton came real close this time.
1. Fox news