"This is a shocking invasion of the governor's privacy and a violation of law. The matter has been turned over to the appropriate authorities and we hope that anyone in possession of these e-mails will destroy them," the McCain campaign said in a statement.
The Secret Service contacted The Associated Press on Wednesday and asked for copies of the leaked e-mails, which circulated widely on the Internet. The AP did not comply.
The disclosure Wednesday raises new questions about the propriety of the Palin administration's use of nongovernment e-mail accounts to conduct state business. The practice was revealed months ago - prior to Palin's selection as a vice presidential candidate - after political critics obtained internal e-mails documenting the practice by some aides.
One person whose e-mail to Palin apparently was among those disclosed, Amy B. McCorkell, declined to discuss her correspondence. "I do not know anything about it," McCorkell said. "I'm not giving you any comment." Wired.com said McCorkell later confirmed that she did send the e-mail to Palin.
Another of the e-mails apparently revealed Wednesday was an exchange in July with Alaska Lt. Gov. Sean Parnell discussing a talk show host who had been critical of Parnell. Parnell declined to discuss the matter.
Palin herself used "gov.sarah" in one of her e-mail addresses, but the hackers targeted her "gov.palin" account. Her husband used "fek9wnr" in his address. "Fe" is the representation for iron, and "k9" is an abbreviation for canine. Todd Palin was the winner of the grueling Iron Dog snowmobile race, and "fek9wnr" also is Todd Palin's vehicle license tag in Alaska.
It wasn't immediately clear how hackers broke into Palin's Yahoo! account, but it would have been possible to trick the service into revealing her password knowing personal details about Palin that include her birthdate and ZIP code. A hacker also might have sent a forged e-mail to her account tricking her into revealing her own password.
McCorkell was appointed by Palin to an advisory board on issues involving alcohol and drug abuse. One of the leaked e-mails suggested McCorkell wrote to Palin on Sunday to say she was praying for Palin. "Don't let the negative press get you down!" the message said.