Vodafone (NZ) is reporting that they have shut down their email service as of November 30, 2017.
This affects the following domains: clear.net.nz, es.co.nz, ihug.co.nz, paradise.net.nz, pcconnect.co.nz, quik.co.nz, vodafone.co.nz, vodafone.net.nz, and wave.co.nz.
However, don't purge those addresses from your lists just yet. Vodafone is allowing users to (at least temporarily) continue to receive mail at those accounts, and the mail will be forwarded on to a new email address as configured by the user.
What should senders do? Watch for bounces; bounces will definitely increase at those domains. Those bounces mean that users have not set up email forwarding, and their accounts are thus now closed. You may want to attempt to mail those subscribers, to find the ones whose accounts still forward, to request that they update their email addresses registered with you.