This scam used to be common in postal mail until it was made illegal and the authorities started cracking down on it, but has made a comeback as a new generation of scammers decided that spam email would be a cheap way to get into it.

By sending out enough emails, the scammer can be guaranteed that he will make a large number of correct calls. Here is how it works:

You send out 100,000 emails telling the punters that you have a highly successful futures trading system, they have been subscribed for free to a one month sample subscription of your newsletter. You then tell them you think gold, or oil, or the dollar, or the stock market is going to go up this week.

You send another hundred thousand emails giving the same schtick about your system, but you tell these guys the market is going down.

To the 100,000 recipients that did in fact get an email with the correct call, you send out 50,000 "up" calls, and 50,000 "down" calls.

To the 50,000 recipients that have had two correct calls in a row, send 25,000 "up" and 25,000 "down".

To the 25,000 recipients that have now received three correct calls, you send 12,500 "up" and 12,500 "down". Make sure you boast a lot and point out repeatedly that this is the fourth correct call in a row.

To the 12,500 recipients that have had a stunning four correct calls, you send 6,250 "up" and 6,250 "down".

By this stage you have had so many good calls that people might forgive a single bad call, so if you want to you can send another call to the people that have had four correct and one wrong, you will pick up another 3,125 people this way that have had at least five correct calls.

Now that 6,250 people have received five consecutive correct calls, you can market to them. Remind them of how much money they could have made this month trading futures contracts based on your calls, tell them that most of your clients are multimillionaire full time futures traders that now live a life of luxury on a private beach somewhere.

And then you try flogging them a $5,000 black box software package. If 2% of the 6,250 take you up on your offer, you've just sold 125 packages, and made a cool $625,000.

Repeat until rich.