The Union for Postal Workers is worried a scam that has conned New Zealanders out of millions of dollars is circulating for a fourth time.

The scam letters from Malaysia contain a travel promotion brochure and two scratchies - one of the scratchies is usually a "2nd prize" of between USD$150,000 (NZ$247,035) and US$250,000 (NZ$411,725).

The prize money can alledgely be claimed by sending thousands of dollars to 'cover the tax required' by the government of Malaysia.

John Maynard from the Postal Workers Union said the scam letters are easy to spot due to their distinctive colourful Malaysian stamps, a stick-on label using a person's surname followed by their initials with no return address.

"They're quite easy for us to identify, but people who think they're the only ones who might have got this may be sucked in."

The police said similar mail frauds, in 2013, 2016 and 2019, fleeced New Zealanders of millions of dollars.

Maynard said he has direct experience with one of these previous scams, and, after being on the receiving end of one of the letters in 2019, decided to visit the address listed as the 'Government of Malaysia' during a trip to the country.

" went to the Kuala Lumpur office listed on what I knew was a scam '2nd prize' ... that I had received in the mail before travelling overseas," he said.

Unsurprisingly the address on the 'prize' letter was actually a park; the Malaysian Government's Pension Fund building, which the fraudsters were using as a front., was just across the road.

"I left my '2nd prize' ticket with the Malaysian government representatives to alert them about their building being used as a front to scam millions of dollars from residents in Aotearoa, New Zealand," he said.

-RNZ.