If you've had an email account for longer than 12 months, then you've probably received hundreds of emails over the past few years from Nigerian princes willing to share their money, or others soliciting money to help get their ridicously large amounts of money out of the country from their father's/uncle's/brother's/ex-boss's/close friend's estate. In all cases, you are promised a large of money if you help by sending money to cover the 'transaction fees' required to release the money.
But after all this time, why are you still receiving these emails? At this point, it would seem that every email user would, upon seeing that the email comes Nigeria, have multiple red flags to ignore the claims in the email message. Don't you?
Well it seems that the scammers are smarter than we might think. According to a study written by Microsoft researcher Cormac Herley Cormac Herley, the scammers are intentionally referring to Nigeria in order to weed out intelligent Internet users.
Through this process, the scammers are substantially increasing their odds of finding someone dumb enough to fall for their offer. This form of target selection is important because this self selection process lets the scammers focus more time on those more likely to fall for their scheme.
I recommend reading the report in it entirety. It's a good glimpse into the world of the scammers.