This is just a new twist on the old Nigerian 419 scams, which have been around for decades. Previously you would have received a letter claiming you had won a lottery or inherited a fortune (sometimes as much as US$250,000,000, very tempting). As technology improved it was a fax, then an email. In all cases you would be asked for an account number for the funds to be transferred to, and then, voila! you're left with an empty account.
In the worst cases I have heard of, some gullible souls were further contacted and lured to Nigeria with the promise that there had been a hold-up and the transaction could only be completed in person. Upon arrival, they were kidnapped and held for ransom. Needless to say, there were no happy outcomes to these tales, regarless of whether or not payment was made.
NEVER respond to one of these messages or anything similar. There is, I believe, a branch of your US Treasury Dept that deals with these, but I don't have the website.