My understanding it is fairly easy if your server is in the US. Karr at one point was using a Canadian server. WHich made it more difficult.
One of the teachers in our school system had an "ad" placed on a server in Thailand....possible by a former student. He was unable to get rid of it and immediately notified the authorities who were only able to trace it to a Thailand server. It remains today.
I was responding to: "It would be impossible for me to find out who you were..." Thinking in terms of net/email users with average tech/internet knowledge.
However, you're right. With a bit of tech/web savvy it is fairly easy to use multiple off-shore proxies, which make it extremely difficult to trace someone on the net.