I think there are a couple of things to take note of about the whole Hillary Clinton private email server issue while Secratary of State (2009-2013) ...

... aside from the fact that it's got its own Wikipedia webpage now (be curious to see its Table Of Contents evolve this summer) -

https://en.wikipedia.org/wiki/Hillary_Clinton_email_controversy

Contents

• 1 Background
  • 1.1 BlackBerry phones
  • 1.2 Domain names and email server
  • 1.3 Initial awareness
• 2 Use of private server for government business
  • 2.1 May 2016 report from State Department's inspector general
• 3 Server security and hacking attempts
• 4 Classified information in emails
  • 4.1 Inspector general reports and statements
  • 4.2 FBI investigation
  • 4.3 Journalists and experts
• 5 Responses and analysis
  • 5.1 Clinton's response
  • 5.2 Democratic response
  • 5.3 Republican response
  • 5.4 Later responses by Clinton
  • 5.5 Comparisons and media coverage
• 6 House Select Committee on Benghazi
  • 6.1 Subpoenas for State Department testimony
  • 6.2 Allegations of politicization
  • 6.3 Clinton's testimony at public hearing
• 7 Freedom of Information lawsuits
  • 7.1 Judicial Watch v. U.S. Department of State
  • 7.2 Jason Leopold v. U.S. Department of State
  • 7.3 Associated Press v. U.S. Department of State
  • 7.4 Other suits and coordination of email cases
• 8 References
• 9 External links  

Some things to note -

First of all, (content and findings aside) if such a report were researched and released by a US Congressional Investigative body that was controlled by the Republican Party (or any body controlled by the GOP for that matter), then it could be - rightly- be construed and questioned as a partisan attack against Secretary Clinton. That this came from the current OIG as housed in the current (Obama-Kerry) Department of State makes it very clear this effort is non-partisan and objective.

And second and perhaps more important to note, either Obama and/or Kerry could have at any point delayed or quashed this report. That they didn't speaks volumes not only in their confidence in Mr Linick, but that they weren't going to interfere. 

BTW - here's that link again - read it yourself -

https://oig.state.gov/system/files/esp-16-03.pdf.

You can say what you want, but as far as I'm concerned, this is really bad for Clinton. Because you can be reasonably certain, her political adversaries - especially those on the right-wing - will use this against her throughout the campaign were she to be crowned the Democratic Party Presidential nominee. 

There's a very easy way for the Democratic Party to avoid all this - go with the candidate who can write an email without causing controversy - Bernie Sanders.