Well since you posted the email address,,,,
there's probably not a lot the FBI can do.
Going to http://www.dnsstuff.com/ and doing a WHOIS lookup on the domain name "teensseks.com", it is registered to an owner in Khomutov, CZ.
CZ being Checkoslovakia.
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If you get stuff like this in your email, the best thing to do is just forward it to your own ISP with a "mild" complaint. That way they can add the domain to their spam list to attmept to prevent any further emails from the domain "teensseks.com" from getting anywhere on their mail servers, and they can do a check quickly to detirmine if any law-enforcement agencies in your country (wherever you happen to be located) would be useful to inform or not.
Much of the time, it's "not".
There is no use bothering the FBI for example, for an offender on the opposite side of the world.
Assuming such content is illegal in your country (as it is in most) your ISP wants no part of it on their servers--and they are in a better position to handle that aspect of it than the government is.
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