US Vice-President Mike Pence has been accused of hypocrisy after it emerged he used a private email as Indiana governor to conduct state business.
He contacted advisers on terrorism and homeland security via an AOL account during his four years as governor, though he did nothing illegal.
The new Indiana governor has released 30 pages of emails after a public records request, but withheld others.
Mr Pence was a vocal critic of Hillary Clinton's private email server set-up.
His email account was hacked last summer when many of his contacts received emails saying Mr Pence and his wife had become stranded in the Philippines and urgently needed money.
Mr Pence apologised to his contacts and changed his email address.
But on Thursday he rejected any suggestion that his email situation had been the same as that of the former Democratic presidential candidate.
"No, there's no comparison whatsoever between Hillary Clinton's practice of having a private server, mishandling classified information, destroying emails when they were requested by the Congress and by officials," said Mr Pence.
"We have fully complied with all Indiana's laws. We had outside counsel review all of my private email records to identify any emails that ever referenced or mentioned business, state business-related activities.
"And, as Indiana law requires, we transferred all of those to the state of Indiana, subject to the public access laws."
Is Pence a hypocrite? - Anthony Zurcher, BBC News, Washington
Cue the "lock him up" chants by Democrats still raw over Republicans who excoriated Hillary Clinton amid the private email story in 2016.
As with Mrs Clinton's case, there are now concerns that Mr Pence did not rigorously comply with government archiving and open-records guidelines.
There are a few key differences between the former secretary of state and current vice-president, however. Where Mrs Clinton used her own private email server, Mr Pence - just like your grandparents - relied on an America Online account.
There is no evidence that Mrs Clinton's email was illegally accessed, while Mr Pence's account was hijacked by hackers who sent out correspondence to the governor's contacts saying he was stranded in the Philippines and in urgent need of money (to be wired to the hackers, of course).
Although Mr Pence did use his AOL account for messages about state security and discussions of FBI correspondence, there currently are no allegations he dealt with highly classified information. Mrs Clinton had at least some top secret information on her server.
Still, it seems that while Mr Pence was throwing rocks at the Democratic nominee last year, he was living in a digital glass house.
His successor as governor, Eric Holcomb, declined to release an unspecified number of emails from Mr Pence's account, stating that they contain sensitive or confidential information, including that related to homeland security.
But former US President Bill Clinton's adviser, Paul Begala, said Mr Pence was guilty of "staggering" hypocrisy.
"I'm trying to choke down the vomit," Mr Begala told CNN. "I'm sickened. It's too spectacular. Irony has not only died, it drank a gallon of antifreeze, climbed to the top of the Washington Monument and threw itself off.
"There is no more irony in America."
Indiana law does not prohibit the use of a private email account.
But the legislation is generally interpreted to mean that communications related to official government business must be retained for public records, according to the Indianapolis Star, which broke the story.
Government transparency campaigners say Mr Pence's AOL account missives would not have been automatically recorded for public record-keeping purposes.