Susan Quean, a 75-year-old grandmother, said the letter arrived personally addressed to her in a fancy-coloured envelope and with a distinctive company logo titled Benson Charles & Associados.

"When I first read the letter, I was a little suspicious even though they had spelt my surname, which is an unusual name, correctly," she said.

"The letter said they were from a law firm representing someone with a similar name to mine who had been killed in a car accident overseas and had left $7.5 million 'with one of the banks in Portugal'.

"They asked for my bank and contact details to deposit this money and the letter was signed. I had never received anything like this before."

Mrs Quean said she showed the letter to her daughter who immediately raised the alarm.

A Google search of the name Benson Charles & Associados revealed that the scam dates back to 2005 and with slight variations to the name.

"I want to warn others, particularly the elderly, who may receive similar such letters. I would never give away my bank details but when you receive a letter like this it can be a little scary.

"It made me wonder how they got my name, address and phone number. I don't use a computer and I don't have an email address."

Mrs Quean said she would forward the letter onto police.