The Department for Education's private emails are subject to Freedom of Information laws and Whitehall will have to disclose the information, it has been ruled.
The Information Commissioners' Office released a statement on Friday saying the information contained in the emails "amounted to departmental business and so was subject to freedom of information laws".
This means the department is now legally required to disclose the requested information or issue a refusal notice in accordance with the FOI Act. Despite the information being sent from a private account, as opposed to a departmental email account, the information sought after in the FOI request was held on behalf of the DfE.
The email in question which started the private email storm was sent from Gove's wife's "Mrs Blurt" account, and set out the DfE's communications strategy and discusses a forthcoming judicial review against the department.
Infamously, Gove summarised he feelings towards the case saying: "AAAAAARGGGGGHHHH!!!!!!"
Despite being told private emails and texts discussing official business are subject to FOI laws, Gove announced in January he would be waiting on "fresh advice" before responding to the requests.
The use of private emails to conduct departmental business was first revealed in August by The Huffington Post UK after an email was leaked showing Whitehall officials pressuring a school into becoming an academy.
Meanwhile an investigation by the Financial Times asked civil servants to release the emails under the FOI act. The Times was told the messages, which reportedly discussed replacing personnel in the DfE, could not be found.
The allegations followed an email sent by Gove's chief political aide Dominic Cummings in February, which stated he would no longer be answering emails sent to his official department account.
"I will only answer things that come from gmail accounts from people who I know who they are. I suggest that you do the same in general but thats obv up to you guys - I can explain in person the reason for this."
The education secretary had attempted to defend his department's actions over the emails when he appeared before the Commons Education Committee in January.
He confirmed that the department's own chief freedom of information adviser had ruled last May that private email accounts are covered by transparency laws introduced under the previous Labour administration.
But he told the committee that this advice conflicted with that of the Cabinet Office, which said that anything held in a private email account was not subject to disclosure under FOI.
Gove said: "We followed the advice we received from the Cabinet Office."
A Department for Education spokesman said:
"Emails are not automatically considered an official record. Special advisers are not required to maintain records of deleted emails. All civil servants routinely delete or archive emails, taking account of their nature and content.
"Government systems could not operate if every civil servant kept every email they send or received. The act of deleting emails is not evidence of wrong doing."