Is it a federal offense to send an email impersonating an FBI agent?

[BuelahWitch]

I got an email in my spam box today that was supposedly sent by FBI director Robert Mueller. It says I (the "undisclosed recipient")have been caught having an illegal transaction with the Bank of Nigeria and they want $150 sent through Western Union for some investigation.
Now, I know that if I was really doing something horrible on the internets that warranted an FBI investigation, I'd get a knock at my door, not an email about it. But the other "undisclosed recipients" might see it and freak out. I went on the FBI site and saw that I could report a scam, but I wasn't scammed. I figure the person doing it has to be either pretty ballsy or pretty stupid.
After checking the headers it appears that it originated in Australia. Can anything be done if it's not domestic?

[Hawkeye-X]

1. Nothing to do.

One of our client's servers were filled with spam to be sent out - most of them were Nigerian spams with "RObert Mueller"

Just ignore 'em.

Hawkeye-X

[Historic NY]

2. Oh my thats a new angle for them in their 419 schemes....pretend

the victim is the bad guy.

http://www.fbi.gov/majcases/fraud/fraudschemes.htm

[BuelahWitch]

4. Yeah, that's what I thought, scare people into sending them money

Very sad.

[bean fidhleir]

3. Report it. The Feebs should lay it off on the cops in Oz, if that's indeed where it's from.

It is, indeed, a crime to impersonate a federal agent for the purpose of fraud. Or impersonate anyone, for that matter, to further a fraud.