Jan 5, 2013
You can report it to http://www.ic3.gov/complaint/default.aspx but they won't act on any one complaint.
Sending fake checks through the mail is a crime so contact the US Postal Service Inspectors https://postalinspectors.uspis.gov/forms/MailFraudComplaint.aspx
It's difficult to stop scams like these in real time. The only thing we can do is to warn others and to try to cripple his scam operation as follows. If you received an email and can read headers or know someone who can, you can report abuse to the sending email service and have his account terminated. Ditto for his reply email address if different from his sending address. This will only slow him down, it will not stop him.