In March of 2015 , the president told the press that the first he had heard of Clinton's private email server was through press reports. But Clinton never obtained a State Department email address, using clintonemail.com, which connected to her private server. How is it possible the president failed to notice that his emails were not going through official channels?

FBI files released on Friday indicate that President Obama used a pseudonym in at least some of his email exchanges with Hillary Clinton. The revelation shocked Clinton aide Huma Abedin, who wondered why the emails weren't classified.

And why would President Obama use a fake name to communicate with his secretary of state?

Politico:

The 189 pages the bureau released includes interviews with some of Clinton’s closest aides, such as Huma Abedin and Cheryl Mills; senior State Department officials; and even Marcel Lazar, better known as the Romanian hacker “Guccifer.” In an April 5, 2016 interview with the FBI, Abedin was shown an email exchange between Clinton and Obama, but the longtime Clinton aide did not recognize the name of the sender. "Once informed that the sender's name is believed to be pseudonym used by the president, Abedin exclaimed: 'How is this not classified?'" the report says. "Abedin then expressed her amazement at the president's use of a pseudonym and asked if she could have a copy of the email." The State Department has refused to make public that and other emails Clinton exchanged with Obama. Lawyers have cited the "presidential communications privilege," a variation of executive privilege, in order to withhold the messages under the Freedom of Information Act. The report doesn't provide more details on the contents of that particular email exchange, but says it took place on June 28, 2012, and had the subject line: "Re: Congratulations." It may refer to the Supreme Court's ruling that day upholding a key portion of the Obamacare law.

I'm sure there's a reasonable explanation for all of this, right? I mean, there's no way that Obama and Clinton were trying to hide anything from public disclosure.

The most transparent president in history used a fake name to communicate with one of his key advisers. If we can assume he wasn't trying to hide his identity from Clinton aides, the only explanation that remains is that he was trying to hide his identity from you and me.

Only a few media outlets have picked up on Obamas' use of a pseudonym when communicating with Clinton. This would be an extraordinary revelation if it involved just about any other president, but for Obama, it is only a passing curiosity.