Spark has responded to customer concerns about ongoing problems with its Yahoo! and Outlook Express email accounts.
Some Spark customers have reported continuing email issues, which have prevented them sending and receiving emails.
Not all customers are affected.
A Spark spokeswoman said Spark had been working with SMX, a leader in email security, to move away from Yahoo! and bring Xtra mail home to New Zealand.
''We asked all our customers to give us their permission to be moved.
''Now we have collected all the permissions, we are preparing to move the actual data.''
She said in light of all the highly publicised incidents of email data theft, and in order to protect Spark customers, Spark was also upgrading Xtra mail's email security.
''Without getting too technical, support for the RC4 cipher which was first designed in 1987, has been ended.
''The RC4 cipher is a type of security setting that isn't encrypted sufficiently for today's standards.
''It's a change that's happening all over the world for a range of different applications, as developers shift to newer, safer technologies with higher encryption standards.
''What this security upgrade has meant, is that a few customers may be experiencing problems accessing Xtra mail when using an old, outdated third-party mail client.''
Because older email configurations were at far greater risk of being exploited by security vulnerabilities, Spark recommended customers on older operating systems and email clients (such as Outlook Express), upgrade to better ensure their security.
