Telecom says it will continue to offer its Yahoo! Xtra email service despite a serious security breach earlier this year.
The company has reviewed its partnership with the email provider after almost 90,000 had their email accounts used to send out malicious spam as part of a cyber attack in February.
Retail chief executive Chris Quin said on Friday the review found that Telecom broadband customers value the email service and 200,000 customers have changed their email passwords since the attack.
Mr Quin said customers should remain confident in Yahoo!
"They should have the same level of confidence in the security of this service as you would have in any online service.
"At times, up to 90 percent of the email that moves around the world is spammed, so this is a universal issue across all of the services, whether it be Google, Yahoo! or any other mail service."
Mr Quin says Telecom and Yahoo! are working to improve security and communication with customers whose accounts have been compromised.
At the time of the attack, Telecom said Yahoo! Xtra had assured it that the accounts had been hijacked only to send spam rather than to steal personal details.