Editor’s Note: This report first appeared in the New York Times — newsworthy in and of itself. We reprint in part here.

WASHINGTON — Hillary Rodham Clinton exclusively used a personal email account to conduct government business as secretary of state, State Department officials said, and may have violated federal requirements that officials’ correspondence be retained as part of the agency’s record.

Mrs. Clinton did not have a government email address during her four-year tenure at the State Department. Her aides took no actions to have her personal emails preserved on department servers at the time, as required by the Federal Records Act.

It was only two months ago, in response to a new State Department effort to comply with federal record-keeping practices, that Mrs. Clinton’s advisers reviewed tens of thousands of pages of her personal emails and decided which ones to turn over to the State Department. All told, 55,000 pages of emails were given to the department.Mrs. Clinton stepped down from the secretary’s post in early 2013.

Her expansive use of the private account was alarming to current and former National Archives and Records Administration officials and government watchdogs, who called it a serious breach.

“It is very difficult to conceive of a scenario — short of nuclear winter — where an agency would be justified in allowing its cabinet-level-head officer to solely use a private email communications channel for the conduct of government business,” said Jason R. Baron, a lawyer at Drinker Biddle and Reath who is a former director of litigation at the National Archives and Records Administration.

A spokesman for Mrs. Clinton, Nick Merrill, defended her use of the personal email account and said she has been complying with the “letter and spirit of the rules.”

Under federal law, however, letters and emails written and received by federal officials, such as the secretary of state, are considered government records and are supposed to be retained so that congressional committees, historians and members of the news media can find them. There are exceptions to the law for certain classified and sensitive materials.

Mrs. Clinton is not the first government official — or first secretary of state — to use a personal email account on which to conduct official business.

But her exclusive use of her private email, for all of her work, appears unusual, Mr. Baron said. The use of private email accounts is supposed to be limited to emergencies, experts said, such as when an agency’s computer server is not working.

“I can recall no instance in my time at the National Archives when a high-ranking official at an executive branch agency solely used a personal email account for the transaction of government business,” said Mr. Baron, who worked at the agency from 2000 to 2013.

Regulations from the National Archives and Records Administration at the time required any emails sent or received from personal accounts be preserved as part of the agency’s records.

But Mrs. Clinton and her aides failed to do so.

Read the full story.