Culture Secretary Jeremy Hunt has admitted he uses his personal email account to conduct government business.
Officials monitor his departmental address and show him anything he needs to see while he exchanges messages with contacts using gmail, the Leveson Inquiry heard.
The admission comes after Cabinet colleague Michael Gove was criticised last year for appearing to circumvent officials by using a domestic account.
Hunt was being quizzed about a message sent by his former special adviser Adam Smith when he admitted he shunned the government email system.
The email, sent on October 7, 2010, and entitled "note from Fred", contained information about News Corporation's plans. Smith said the contents were commercially confidential "but very interesting".
Hunt replied: "Very powerful actually." Asked why the exchange was conducted on his gmail account, Hunt said: "That's the only email account I use. My department email gets looked at by my private office and if there is anything they need to show me they show me. But the only email account I use is my personal account."
The Information Commissioner "raised concerns" last September about the way requests for information were handled by Education Secretary Michael Gove's department after claims that government business was conducted using personal email accounts.
Last week Gove defended his use of the personal account, which has the name "Mrs Blurt", claiming he turned to it because he could not get to grips with his department's computer system.
"I sent personal emails simply because the one thing that did frustrate me in the Department for Education was its IT and its software which I could never get the hang of," he told the BBC.
"The computer and, what's it called, the BlackBerry that I had, I just didn't find congenial so I cracked on with my own Apple. The critical thing about the department is that even if its IT might be ropey, its staff are fantastic."
The department is appealing against a decision by the Information Commissioner that it should disclose the emails under the Freedom of Information Act, unless it can provide a valid reason for not doing so.
Gove said: "There needs to be a space where civil servants can talk frankly to ministers, and advisers can talk frankly to ministers about policy, and they can run through things.
"The only way that we can get good policy is by having people encouraged to be radical, not being worried they will be laughed out of court for it."