SENIOR civil servant Andrew McCormick has said the only email address he ever used to correspond with Jonathan Bell was the DUP minister's Hotmail account.
Mr McCormick said it was "not good practice" but it "became expedient" to send government papers to ministers' personal email accounts rather than through proper Stormont IT systems.
He told the RHI inquiry is was reasonably common with ministers from all political parties to use personal email accounts for government business.
Mr McCormick said he had a "similar trail of emails" to a personal account for the DUP's Simon Hamilton, who was economy minister and succeeded Mr Bell in having responsibility for RHI.
Mr Bell has denied using his Hotmail for ministerial business, but the inquiry has previously heard of the email address being used for correspondence to and from various departmental officials.
The issue arose yesterday as Mr McCormick told the inquiry he sent details of an RHI whistleblower's claims to Mr Bell's Hotmail address.
He said: "It was the only email I ever used."
Inquiry panellist Dame Una O'Brien asked: "Were you satisfied with doing this degree of government business over a Hotmail account?
"Because it does strike me as unusual to be conveying this and other documents outside of the department's system."
Mr McCormick, former permanent secretary in Stormont's enterprise department, said: "I have a similar trail of emails to Simon Hamilton's personal email account. It became expedient."
"It's something where we weren't taking it on seriously as an issue. We just allowed it to go ahead as a way of working."
"It's not good practice. It's not secure," he added, but said it was "not a great harm either" when exchanging less sensitive information.
