A spokeswoman for the Prime Minister confirmed tonight that that email address "doesn't even exist" and said it was clearly not John Key's email.
"So it's kind of ridiculous.
"...it's not a correct email address and I imagine quite a few of them won't be," she said.
Of the file released, there are reportedly an estimated 22,000 New Zealanders using the site, with 32 accounts linked to New Zealand government agencies.
Among the email addresses mentioned, there are some from the Ministry of Justice, Corrections, Police, and various district health boards and regional councils around the country.
There is also a Parliament email address, as well as ones from the Department of Conservation and the Ministry of Social Development.
A spokesman for the State Services commissioner said if the email addresses were correct, it would appear to be an "inappropriate use of government resources" and could be in breach of the state sector code of conduct.
He said they had not seen the names, however, and that it was only alleged at this stage.
It would be up to the chief executives of the different government organisations to examine if this was a breach of their own code of conduct or policy, the spokesman said.
He said the commissioner's position is that he will be reminding the chief executives that it is important that their individual policies are followed and that there is no inappropriate use of government resources, such as email.
If the 9.7 gigabyte leaked file proves to be genuine, it could still expose the secrets of millions of authentic married customers who use Ashley Madison to carry out affairs.
The service promises its 37 million members worldwide complete "anonymity" and has the motto: "Life is short. Have an affair".
Last month, hacking group the Impact Team claimed they had stolen their details and threatened to publish all names, addresses, credit card details and sexual demands unless the site was shut down.
Today's dump appears to have all these details, with files that contain titles such as "aminno_member_email.dump.gz," "CreditCardTransactions7z," and "member_details.dump.gz", according to Ars Technica.
Impact Team says Ashley Madison members should not have anonymity because they are "cheating dirt-bags and deserve no such discretion".
The hackers also stole details for members of Cougar Life, a website for older women who want to date young men, and Established Men, which helps "successful" men meet "young and beautiful women".
They asked for Established Men to be taken offline, along with Ashley Madison, but did not make the same request of Cougar Life, suggesting they are more interested in exposing unfaithful men.
"Avid Life Media has failed to take down Ashley Madison and Established Men," Impact Team wrote in a statement accompanying the online dump earlier today.
"We have explained the fraud, deceit, and stupidity of ALM and their members. Now everyone gets to see their data.... Keep in mind the site is a scam with thousands of fake female profiles.
"See Ashley Madison fake profile lawsuit; 90-95 per cent of actual users are male.
"Chances are your man signed up on the world's biggest affair site, but never had one. He just tried to. If that distinction matters."
The hackers said the consequences for victims of the breach was not their responsibility.
"Find yourself in here? It was ALM that failed you and lied to you. Prosecute them and claim damages.
"Then move on with your life. Learn your lesson and make amends. Embarrassing now, but you'll get over it," they wrote.
One British Ashley Madison user, called Natalie, is one of the 1.2 million in the UK scared her husband will discover her infidelity.
She says that she started using the site during a "rocky patch" in her marriage, but has not logged since 2011.
She told The Sun last month: "Things with my husband improved and I haven't logged in to the website in years. Now I feel sick to my stomach that my past could come back to haunt me".
Canadian owners Avid Life Media believe a company insider may have helped hackers grab the information.
CEO Noel Biderman, the self-styled "King of Infidelity" who set up the website with his wife Amanda, believes that a hacker with ties to the site's technical services is the culprit behind the privacy breach.
"I've got their profile right in front of me, all their work credentials. It was definitely a person here that was not an employee but certainly had touched our technical services," Biderman told Krebs On Security.
Last month, experts warned the stolen data could be sold on to criminal gangs or used to blackmail members.
One hacking insider, named only as Vinnie, told Sky News the valuable data will likely be sold on the "Dark Web" to "the highest bidder".
The cyber criminals had previously only published a small amount of the information online.
The hackers have claimed that even cheaters who have paid Ashley Madison to delete their information from its files are at risk - making the site millions, but claim these details were never fully deleted.
The website charges members £15 for what it says is a "full delete" of information that should leave no footprint. However, the hackers claim this service was a "complete lie".
"Users almost always pay with credit card; their purchase details are not removed as promised, and include real name and address, which is of course the most important information the users want removed," they said.
The security breach is bad news for Ashley Madison, which has been battling to gain respectability after it was dubbed the "Google of cheating".
It even hoped to float on the London Stock Exchange later this year.
The Canadian company said in April it thought British investors would be more likely to buy into the business because Europeans have a more "laissez-faire" attitude to cheating.
However, even open-minded Europeans found Ashley Madison' attempts to make money from adultery a step too far.
Many of the brokers it would have relied on to sell shares in Britain refused to deal with the company, amid concerns that it leads to family breakdowns.
-Daily Mail, nzherald.co.nz
