Spam traffic was worse than ever yesterday, the first day of legislation banning the practice.
Anti-spam specialists SMX recorded a major spike in traffic, peaking at 1am one hour after the law came into effect.
Spam volumes were up 20 per cent on an average day.
SMX director Jesse Ball said the volume of spam had been "incredible" in the last two weeks.
"It's been the biggest growth in spam we've seen. Everything is building day on day it's a huge increase.
"We had a bit of spike towards the end of last year but we've absolutely surpassed those volumes."
Joe Stewart, anti-spam compliance manager, for the Department of Internal Affairs, said 13 complaints had already been laid about illegal spam. Five of those were considered likely to be in breach.
"One of my investigators has been on the phone all day. It's a goldmine of information," he said.
Four spammers were known to operate in New Zealand and the department had them in its sights already. One of the spammers had identified himself by ringing up the department and abusing it.
Hundreds of businesses had also phoned through to check if they were complying with the law. Most had some form of consent from recipients so were operating within the law.
Ball said the spike in spam was probably linked with Americans going back to work after their summer holiday.
There was a 50% increase in total spam messages in August.
Wellington author Richard Meros claimed the title of "the last legal spammer". Meros sent off a "rather tipsy" message to media organisations moments before the law took effect.
Meros is an ardent critic of the law.
"There are so many worse forms of advertising around. There just seems to be no point in this. The New Zealand ones offer great things like paua shell decorations."
Meros was worried there were jobs at stake with the ban.
"We've got these spam-bots out there doing a great job and now they're going to lose their jobs."
Meros, who has spammed to promote his books in the past, said he "just might" do it again.
- The Press