Former Secretary of State Hillary Clinton isn't the only big-name government official using a private server.

An exclusive NewsChannel 5 investigation discovered that Tennessee Gov. Bill Haslam also has his own email system -- for him and his top aides.

That email is linked to the governor's personal website, billhaslam.com.

In principle, experts agree that having a private email to make sure that state email is not used for political purposes is a good thing. The question is: what happens when that private email is used for public business?

"This is what got Hillary Clinton in trouble, and so I think the public sees this as an issue," said Deborah Fisher, executive director of the Tennessee Coalition for Open Government.

Fisher questioned whether public business is being conducted out of the public eye.

"By using a private email account, while those emails may still be subject to the Public Records Act, they are essentially under the radar and nobody knows about them," she added.

NewsChannel 5 Investigates filed a public records request to obtain a snapshot of emails caught up in the state's computer system sent to or from the governor's private server.

The governor's office said it withheld 18 documents because they were "deliberative" in nature, contained confidential economic development information or included secret tax information.

Still, we found state budget officials -- from state accounts -- briefing the governor himself at a billhaslam.com email address.

The governor's executive assistant, Janet McGaha, also uses billhaslam.com, corresponding in a couple of cases with then chief-of-staff Mark Cate -- again at billhaslam.com.

We showed the emails to Nashville Tea Party activist Ben Cunningham.

"Obviously, they are using this private server to discuss public business," Cunningham said. "Those are public records."

In one example, Cate used that account to email an education activist about Common Core, copying Haslam's education commissioner -- also apparently using private email.

In another case, a lobbyist emailed Cate at billhaslam.com about a letter he wanted the governor to sign.

Cate sent it on to the governor's policy director, Will Cromer, also at billhaslam.com.

The governor's office says any use of that account for official government business was "inadvertent and a rare occurrence."

And like Hillary Clinton, officials say the fact that such emails were eventually forwarded to the state email system shows they weren't trying to hide anything.

The governor's communications director, Dave Smith, added: "Any insinuation that the governor or this office deliberately used non-state emails for official state business is wrong and misleading."

Deborah Fisher said the critical question is whether the Haslam administration routinely searches that email system when responding to public records requests.

"The only thing that would be in violation of the law is if you made a request for records and they only provided you records that they had access to on the government account, yet there are other records out there that they were not providing you," she added.

Meanwhile, after the Haslam administration took office, supposedly to save server space, they changed the rules so that, instead of all emails being kept for six months, they're automatically deleted after three.

Cunningham said, "That's ridiculous. That is absolutely ridiculous. The retention policy needs to be at least five years."

An early Internet entrepreneur, Cunningham rejected suggestions that the deletion policy results in a significant cost-savings.

Fisher added, "If you are going to automatically shred records, there should be some judgment about what you're shredding and not just automatically flushing it out of the system."

As for how long emails are kept on the governor's private server, the governor's spokesperson said: "I have no idea."

Cunningham said that's not an acceptable answer.

"All these decisions these days are made online, they are made with email, they are made with text messages, chat. All this should be retained so that citizens will know how the decisions were made and who influenced the decisions."

Because NewsChannel 5 Investigates only asked for a snapshot from the state email system, we can't independently confirm how often the governor and his aides may use billhaslam.com to discuss government business.

The governor's spokesperson said they did search that account a while back when we asked to see all the governor's emails about a massive contract to outsource state office buildings to a big corporation.

Despite the fact that it was one of the biggest changes ever in how state government does business, for whatever reason, that search produced very little.

Below are the answers from the Governor's Office to three specific policy questions:

Q: Has the Administration ever had a formal policy about the use of billhaslam.com or any other private email for state business? If so, please provide. Just because I have some emails that were captured by the state system doesn't mean that all of them were forwarded there.

A: "No matter the domain, an email created, sent or received in conjunction with the transaction of official business is a public record and should be turned over if it falls within the scope of a records request. Failure to do so would be against the law. We remind staff and Cabinet members of the importance of keeping official state business to state email. In addition, Executive Order No. 20 reads: 'No employee shall make use of the facilities, equipment, personnel or supplies of the State or its agencies for private use or gain, except to the extent that the use is incidental or de minimis or is lawfully available to the general public.' Executive branch employees sign the Acceptable Use Policy for Network Access Rights and Obligations, which reminds everyone that 'email created, sent or received in conjunction with the transaction of official business are public records.'"

Q: Can you provide me any examples where the press/public made public records requests for emails where the Administration searched billhaslam.com (without a specific request to do so) and provided any emails that resulted from that search?

A: "No matter the domain, an email created, sent or received in conjunction with the transaction of official business is a public record and should be turned over if it falls within the scope of a records request. Your question would require an extensive review of all records request responses since 2011. But for example, I can tell you that in response to your JLL request, which didn’t mention the governor’s personal email, we searched his personal account and found nothing."

Q: On a related point, the Administration cut the state's email retention policy from six months to three months after the Governor took office. What is the retention policy for billhaslam.com? Have employees of your Administration ever been given specific guidance about what types of emails must be saved from automatic deletion?

A: "The state retention policy was reduced when the State switched to the use of Microsoft Outlook for its email system because of server capacity. If there is a litigation hold on a certain subject, we are required to save emails. I have no idea what the retention policy is for gmail.com, billhaslam.com, yahoo.com, aol.com, hotmail.com, or any other non-state email service."

View selected emails to/from BillHaslam.com