Former Florida Gov. Jeb Bush owns the server that runs jeb@jeb.org, the personal email account he used as governor to conduct official, political and personal business.

Asked who controls the server that operates that email address, Bush spokeswoman Kristy Campbell responded: “He owns it.”

The server was housed in a state-owned office building during the years that Bush served as governor, from 1999 until early 2007. A Bush source familiar with the situation said there were “digital security” measures in place to protect Bush’s emails, but declined to elaborate on how the server and its data were physically and digitally kept from harm. The aide also declined to elaborate on whether the server was “homebrew,” as an email server housed in Hillary Clinton’s Chappaqua home was described by The Associated Press in a Wednesday report.

Related: Hillary Clinton’s email problem is not going away

Using a personal email address and running the address on a personally owned can help protect emails from subpoenas and other legal actions.

Privately, Democrats have been quick to point the finger at Bush for using a personal email as Clinton has come under scrutiny for not having a government email address when she was Secretary of State. Republicans argue the two situations are far from the same.

The existence of Bush’s private email address was widely known to the public and to the press when he served as governor, and he routinely fielded public and press inquiries himself using the address.

Under Florida’s sunshine law, Bush was required to release the emails that related to conducting state business. Those emails are available online. A Bush aide said there was a process in place to decide which emails fell into that category and that Bush staffers and his general counsel’s office decided which ones to release.

On Thursday, Bush on his Twitter account urged Hillary Clinton to release her emails. “Transparency matters. Unclassified @HillaryClinton emails should be released. You can see mine, here,” he tweeted, including the link to his emails.