Telecom says Yahoo!Xtra's most recent hacking ordeal is "a fact of life" given the prevalence of cyber criminals.
Email users with Yahoo!Xtra accounts were again affected by hacking overnight, just days after tens of thousands of Telecom customers suffered a security breach.
About 1500 accounts that did not have their passwords changed after the earlier Xtra hacking are understood to be affected by the latest breach, RadioLIVE reported.
On February 16, Telecom was forced to cancel 60,000 passwords for compromised accounts, where spam emails were sent to contacts in their address books.
Telecom released a statement today saying the latest breach wasn't anything special.
"Over the past two days, Yahoo! has identified approximately 1500 additional accounts as being potentially compromised by spammers. While this is higher than usual, on any given day up to 100 accounts are tagged as compromised ...
the reality is that this issue is now a fact of life given the global nature of the internet and the increasingly sophisticated tactics of spammers and cyber criminals," it said.
Yahoo! is continuing to assure Telecom that there has been no evidence that the email accounts have been accessed for any other reason than to send spam.
Customers are still being told to change their passwords and Telecom said it will continue to cancel the passwords of any email accounts it believes to be compromised.
More than one third of all Yahoo!Xtra customers have changed their passwords since the problem began on February 9, Telecom said.
Telecommunications Users Association boss Paul Brislen told RadioLIVE the incident would further strain relations between the telecommunications company and its email provider Yahoo!
"Yahoo certainly hasn't lived up to the billing of the world's best email provider in the last little while. Telecom's been left to fend for itself in many respects," he said.
After the previous breach an investigation into the hacking was being carried out and a review of its email service would be undertaken, said Telecom retail chief executive Chris Quin.
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- with additional reporting from nzherald.co.nz