A prolific Australian spammer who sent hundreds of thousands of unsolicited spam messages to New Zealand email accounts has been fined $NZ95,000 ($A84,037).

Wayne Robert Mansfield, who lives in Perth, sent thousands of emails in 2010 to people and organisations in New Zealand promoting seminars held by his company, Business Seminars NZ.

Following more than 50 complaints from members of the public, NZ's Department of Internal Affairs decided to take legal action against Mansfield under the Unsolicited Electronic Messages Act.

In his judgment, released on Wednesday, High Court Justice Edwin Wylie said a number of people who complained to the department said they didn't have any business relationship with Mansfield or his company.

Some also said the email addresses messages were sent to were used for domain name registration only and had no other purpose, while one complainant said they continued to receive emails even after sending an unsubscribe message.

Justice Wylie said it's impossible to know precisely how many messages were sent, but said it seemed probable the number was in the hundreds of thousands, and could have been close to a million.

Mansfield initially co-operated with the department but didn't take any part in the court process.

Justice Wylie imposed a fine of $NZ95,000 and awarded costs of more than $NZ8000 against Mansfield.

In 2006, Mansfield and his Perth-based company Clarity1 Pty Ltd were fined a total of $A5.5 million in the Australian Federal Court for sending 70 million spam emails to about five million recipients between 2004 and 2006.