Some Spark customers are having ongoing Yahoo Xtra email issues, preventing some from sending and receiving emails.
Not all customers are affected.
A Spark spokeswoman said today the issue appeared to be at Yahoo's end.
"We are working closely with the Yahoo team to give them as much assistance as possible so they can fix the issue quickly.''
If people were having problems sending and receiving email through their email application, such as Outlook, they could try accessing via webmail _ xtramail.co.nz, she said.
Spark would update its website with information as the situation changed.
