The best weapon against such Emails is to send back to the known Emailaddress great amount of Spam Email with Attachement.
That should block for a time their Emailaccounts and they lose with slow modem connections a lot of time for their criminal actions.

Best practice is to create a new Email and add the emailadress not only to AA:. Also add the Emailadress of the recipient to BC: and CC:.
The Recipint get 3 of this Email you send 1 time. 
Then add big Data as Attachments (best 2-5 MB). That's for the Recipient a Download Volume of 6-15MB.
But send the Emails only with wrong Reply Address, because if Emailaccount is closed or overfulled you will receive back all the Amount of Emails including the Attachements (6-15MB!!!).

That should be enough to block Emailaccount for longer time.
The only solution for them to take away problems is to download all or to open a new Emailaccount with a different Emailadress (They are no longer reachable for older customers!).

Please by sure, that the message in this letter is not real. It was written to find peoples who are stupid enough to loss money finally at the end of transaction. But they will never see "THE BIG MONEY!"