A boss sending an email to one of his employees doesn't usually make news. But President Obama and Hillary Clinton don't work in your average office.

White House Press Secretary Josh Earnest confirmed Monday that President Obama and Hillary Clinton exchanged emails while she served as his secretary of State. Usually, this would seem completely innocuous, if not entirely trivial. But Clinton's email use has been a hot topic for nearly a week now, following a New York Times report revealeing that she used a secret email account—not a .gov address—to conduct official work at the State Department. The White House has neither defended the unofficial Democratic presidential candidate nor confirmed that she violated the Federal Records Act, which governs record-keeping practices for administration employees.

"[The president] did know Secretary Clinton's email address," Earnest said. "He was not aware of the details of how the server was set up or how Secretary Clinton was planning to comply."

He later added: "I assume he knew what email he was sending it to."

Earnest said that Obama and Clinton would have emailed about "weighty national issues," something that's sure to give security experts pause. Their emails would have been archived within a White House system in accordance with the Presidential Records Act, which preserves the president's emails from his official account.

On Thursday, an unnamed source told The Associated Press that the White House counsel's office wasn't aware that Clinton used a personal account for email correspondence. On Friday, Earnest said that Obama could have learned of Clinton's exclusive use of private email to conduct work, as well as the existence of a secret server in her home, from media reports.

Administration officials are required by law to forward personal emails relating to official business to a government account so that the correspondence can be archived and preserved. Two months ago, Clinton's team started turning over 55,000 pages of emails to the State Department, several months after the agency requested email correspondence from all previous secretaries of state. Of those, 900 pages were forwarded to the House committee investigating the 2012 attack on the U.S. consulate in Benghazi, the same committee that discovered Clinton's sole use of a private account for official business.

Clinton has thus far only tweeted a response about her decision to opt against using an official government account, saying, "I want the public to see my email. I asked State to release them."

Since the story broke, the White House has been in the uncomfortable spot of having to defend Clinton. In briefings inundated with questions on her email use, White House Press Secretary Josh Earnest said "personal email" 41 times in a span of two days.