Since 2014 it has been a law.
http://www.slate.com/blogs/the_slatest/2...etary.html
But as the WLB and Leona Helmsley made clear..... laws are for little people.
http://www.slate.com/blogs/the_slatest/2...etary.html
Quote:Under a law passed this past November, a government official can use private email accounts to conduct government business—but only if that official copies or forwards the email to his or her government account within 20 days. Violating that law can result in disciplinary action but carries with it no criminal penalties. But Clinton’s private emailing occurred well before that law went into effect. According to the National Archives, the official definition of what constitutes a federal record did not “clearly include electronic records” until Obama signed the 2014 law, which represented “the first change to the definition of a Federal record” since the Federal Records Act was passed in 1950. Similarly, it wasn’t until August 2013—six months after Clinton had left office—that the National Archives and Records Administration issued guidance making it clear that email records of some senior officials are permanent federal records.
But as the WLB and Leona Helmsley made clear..... laws are for little people.