Top members of President Trump’s team are alleged to have email accounts on a private server.

Top members of President Trump’s team are alleged to have email accounts on a private server.
According to a recent Newsweek report, “...staffers including Kellyanne Conway, Jared Kushner, Sean Spicer and Steve Bannon have active accounts on a Republican National Committee email system.” 
The extent of their use of this system is unknown.
The media outlet also notes that "making use of separate political email accounts at the White House is not illegal."
However, such activity has been linked to controversy in the past, with the Newsweek piece stating, “the system (rnchq.org) is the same one the George W. Bush administration was accused of using to evade transparency rules after claiming to have ‘lost’ 22 million emails.” 
In fact, that case prompted a law called 'Disclosure Requirement For Official Business Conducted Using Electronic Messaging Accounts' which mandates that a copy of correspondence on RNC servers be sent to federal systems within a specific time period.
There are potential hacking concerns, but critics are also pointing out that just months ago, Trump had blasted rival Hillary Clinton for her use of a private server.
CBS News reports that Trump even suggested she go to jail for her actions, saying in June that she is guilty of “stupidity and bad judgment.”