WASHINGTON – Once again, Hillary Rodham Clinton did it her way, and it could cost her.

Clinton’s decision to eschew government email and use her own private server as secretary of state is raising questions about secrecy, security and the law – including whether she might have deleted important messages tapped into her ever-present BlackBerry instead of preserving them for public scrutiny and history.

At the least, the controversy is a bump on her unprecedented path from first lady to presumed presidential contender.

What we know so far:

What’s different

She did all her official work as the nation’s top diplomat using a personal email account. Federal officials are generally expected to use their agencies’ email systems – the kind of addresses that have “.gov” at the end.

Clinton didn’t use a commercial email server, like Google operates for Gmail, either. She had her own email server, traced to her hometown in Chappaqua, New York. The address: hdr22@clintonemail.com.

Prior secretaries of state also used nongovernment email for work at times or avoided using email much at all. Indeed, the State Department says the current secretary, John Kerry, is the first to have an official “@state.gov” address like other employees use routinely.

The volume of the Clinton documents – she’s turned over 55,000 pages – makes her use of personal email more striking.

What’s wrong?

It raises two opposing sets of questions:

Was Clinton’s email too secret?

A private account could have allowed her to withhold or destroy messages that she’s legally required to turn over for congressional investigations or lawsuits or to make available to the public, the press and historians under open-records law.

Was Clinton’s email too exposed?

A private email server may have left her sensitive government communications more vulnerable to people who shouldn’t see them, such as hackers and spies, because it lacked the heavy security of government accounts.

The answers are fuzzy.

Clinton says she’s turned over all relevant emails to the State Department. The House committee investigating the deadly attack on a diplomatic mission in Benghazi, Libya, has issued subpoenas seeking messages that might not have been divulged.

She hasn’t released any information about her email server and its security features. Private email servers are generally not as reliable or secure as those used by the government or in commercial data centers.

Clinton aides and the State Department both say she never received or transmitted classified information on her private account.

Did she break the law?

That’s to be determined. Her aides say “no.”

Her use of private email appears to conflict with the spirit of Barack Obama’s pledge to make his presidency the most open ever. She stands out even in an administration that has been criticized as failing to live up to that promise.

However, Obama didn’t sign a law requiring the archiving of officials’ emails, including those on private accounts, until last November. Clinton left the State Department two years ago.

Even back when she was in office, according to the White House, it was administration policy for officials to conduct their work on government email accounts. If their work strayed into personal emails, officials were responsible for making sure those messages were preserved for history.

White House spokesman Josh Earnest says the vast majority of administration staffers work on government accounts, which should assure their emails are preserved automatically.

Clinton spokesman Nick Merrill says much of her messaging was email back and forth with her State Department advisers on their government email, so the correspondence was retained on their end. Still, her emails to or from people outside the U.S. government – foreign officials, for example – would not be captured in that way.

After the new law was signed last year, the State Department asked Clinton and other former secretaries of state for email records that should be preserved. That’s when Clinton turned over the 55,000 pages.

Earnest said that if Clinton did in fact collect all of her personal email that was related to her official government work and turn it over, “that would be consistent with the Federal Records Act. And that’s the president’s expectation.”