Third-party groups and their online petitions might not be the only reason people across the country received unsolicited e-mails from the White House, even though that's the explanation given by the administration. 

The White House told FOX News that third-party groups sending online petitions to the official administration Web site could be to blame for a rash of e-mails that have gone out to people who never requested them. The theory is that these groups are including the names and e-mails of members and petition-signers along with the petitions themselves, in turn embedding those e-mails into the White House distribution list. 

The White House has already taken steps to add filters to its site in a bid to reduce the number of people who are receiving these e-mails. 

But online petitions are not the only culprit, and critics say the White House still has some explaining to do. 

Several people who received the White House e-mails have told FOX News they're not members of any organization and have not been advocating for any cause. And they're puzzled over how the White House got their information. 

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"I find it very disturbing and a little scary to say the least," said Sarah Griffith, who got a widely circulated e-mail on health care reform from senior adviser David Axelrod last week. "I have no idea how they got my e-mail address, and they have it." 

Griffith, who works for the American Association of Christian Schools in Washington, D.C., said she got the e-mail in her office account even though she's careful not to use her work e-mail for anything that's not office related. She said she has submitted questions through the Whitehouse.gov Web site using her personal e-mail address, but those questions were never answered. She said she never signed up for any updates or petitions with any group. 

Despite the Axelrod e-mail arriving in her office inbox, she said other employees at the organization did not receive the same message. And the association apparently never sent any employee information to the White House either. 

Anita Donaldson, a stay-at-home mom in Arlington, Va., told FOXNews.com she's received a slew of unwanted e-mails from the White House on everything from health care reform to Father's Day ever since she sent some e-mails to Washington via the FreedomWorks Web site. 

That was not a petition, though. And it was not sent directly through the White House page. She sent the messages, protesting the stimulus package and other proposals, through one of many "action alerts" featured on the FreedomWorks page. The pages allow readers to submit comments to the White House and other government officials through an application called Capwiz. 

"Apparently it has put me on some mailing list," Donaldson said. "I get fairly frequent e-mails on a variety of subjects. ... One was even from Michelle Obama herself." 

She added: "I just delete it." 

CapWiz, owned by Capitol Advantage, is a widely-used online service that sets up a line of communication between everyday people and officials. 

But a company representative said the program does not automatically sign up people for e-mails from the office they're contacting. 

There's also the lingering concern that the Obama team, which during the campaign ran what was arguably the most sophisticated online political operation in history, is somehow complicit in lumping together its official distribution lists with those of outside groups. 

Rep. Darrell Issa, R-Calif., wrote in a letter Monday to White House Counsel Greg Craig that he wants to obtain the "full truth" behind the e-mails. 

He said reports that people received the Axelrod e-mail without having contacted the White House raise concerns that "political e-mail address lists are being used for official purposes." 

Another e-mail recipient, Lisa Kaldrupt of Maine, told FOX News her Axelrod e-mail was sent by a company called GovDelivery. That company, based in Minnesota, bills itself as the world's leading provider of government-to-citizen communication solutions and says its e-mail service provides an automated, on-demand public communication system. 

GovDelivery does extensive work with a bevy of federal, state and local agencies, including a number of Cabinet-level departments. 

But Scott Burns, president of the company, told FOX News he had no comment on whether the White House used his firm to send out the Axelrod e-mails. 

Following the controversy over the e-mails, the White House has added two new filter devices to its "Contact Us" section on its Web site, which could reduce the number of people who receive e-mails unsolicited. 

Now, anybody who fills out a comment on that section must uncheck a box that says, "sign up to get e-mail updates." The box is automatically checked when the page loads, so commenters must take an action to uncheck it. 

Anyone submitting a comment now also must type in two words that appear on the page in a strange font -- a security step similar to one that appears on many commercial Web sites. 

In a written statement released to FOX News Sunday, White House spokesman Nick Shapiro said the White House is working to correct the problem. 

"We are implementing measures to make subscribing to e-mails clearer, including preventing advocacy organizations from signing people up to our lists without their permission when they deliver petition signatures and other messages on individuals' behalf," he said. 

The White House indicated its Web site managers were going to seek out and block online petitions so that people can only sign up for information individually. 

White House officials say they're not intentionally trying to contact people who don't want to be contacted, and they don't want the controversy to deepen. 

But Scott Stanzel, former spokesman for President George W. Bush, said the White House, and not advocacy groups, are to blame. 

"The Obama White House developed their own Web site. They are in charge of Whitehouse.gov and what people do on there. They are responsible for monitoring that and they are responsible for making sure that people can't misuse Whitehouse.gov," he said. "On that point, they failed.
From that respect, the explanation is not thorough and, in my view, places blame where it shouldn't be. They should be looking in the mirror instead of pointing the finger at third parties." 

Shapiro said Sunday that any recipients who got unwanted e-mails can unsubscribe "by clicking the link at the bottom of the e-mail or (telling) whomever forwarded it to them not to forward such information anymore." 

FOX News' Major Garrett, Shannon Bream and Eric Shawn and FOXNews.com's Judson Berger contributed to this report.