How would you feel if a stranger offered you tens, or hundreds of thousands of pounds - millions even? They might tell you that the money's been left to you by someone you've never even met, or is locked up in the bank account of someone who died, but shares the same surname as you. Would you be tempted to find out more? If you are, you may find out it's a scam which could end up costing you a small fortune.

After an 80 year old widow from Bridgend was conned out of £16,000 in a similar scam, X-Ray has been contacted by viewers concerned that they may have been approached by similar fraudsters.

The pensioner, who didn't want to be named, was contacted via email by a scammer who claimed a relative of hers had died in a plane crash, leaving $30 million. She was drawn into a complex email correspondence with the scammer and ended up handing over thousands of pounds, believing it would release the unclaimed money. When the scammer asked for more money, the woman told her daughter who contacted police. The people responsible have never been caught.

Rubelyn James lives in Carmarthen. She contacted X-Ray after receiving a similar message. Rubelyn was emailed photographs of a woman supposedly dying of cancer, as well as pictures of trunks full of dollar bills. After being told to send $2,500 via Western Union to cover transfer costs for the money, she wanted to alert other people to the potential risk.

Companies like Western Union are known to have been used by scammers to receive money because the payments aren't traceable. They even have warnings on their website telling people not to send money to someone they don't know.

But scams like this are becoming increasingly common, with the internet making it easier and cheaper for fraudsters to contact tens of thousands of potential victims at just the click of a button, and it being almost impossible for the police to investigate.

Gillian Beynon and her husband Wynford live in Neath. They received a letter which suggested a distant relative may have died leaving over $13 million dollars, just waiting to be claimed.

Gillian was suspicious that the envelope didn't look official and seemed to be inviting the family to take part in a fraud to secure a share of over $13 million. So she contacted X-Ray to warn other people.

Letters like the one Gillian received are very carefully worded to try and capture your interest, with just enough information to tempt you into finding out more about any potential windfall. In fact, that letter is almost identical to one which was reported as an internet scam almost two years ago . The only differences are the names, dates and amounts of money involved.

But there are sometimes strangers who can help you secure that unexpected legacy. If you've ever watched the BBC series Heir Hunters, you'll know that Fraser and Fraser is one of the largest probate detective firms in the country. But according to partner Neil Fraser, scammers are now taking advantage of the company's name to lend credibility to their scams.

He says since the programme was broadcast, he's been told that scammers have adopted the name of Paul Matthews, who works for the firm, and are sending out letters in his name. They even send links to the Fraser and Fraser web page to make it look real.

With 40 researchers working full time, it's a labour intensive process for Fraser and Fraser. It can take months to find the rightful benefactor to an estate. And because of the scammers, people can be sceptical. When the real Paul Matthews set out to find relatives of Alan Tew who died in Pontypool, Paul has to convince them it's not a hoax.

So how can you tell if you really are about to inherit a small fortune, or if you're being targeted by scammers?

Heir Hunter Neil Fraser advises:

• A traditional and bone fide way of doing this would never ask for money up front.
• The phone number should be a land line phone number.
• They should have an address, and you should be able to visit that address.
• They should never be afraid of meeting you in person.
• Speak to your family, and speak to your solicitor to verify who this person is.
• You should never transfer money to someone you don't know.
• Any fees payable should come out of the money you will receive, you should never have to pay anything up-front.