There is spamming software that sends the email directly to your computer. This makes only one received line in the email making your life many times easier. The computer that is not your computer is the spamming computer. Also, please look through the body of the message for email addresses to reply to. Looking below we see 6 received lines.
Received lines are like links in a chain.
The message is passed from one computer to the next with no breaks in the chain. Domain names only have alphabetic or numeric characters in the name. Next would be a traceroute. Kamiel tells us that you might also want to make sure that the IP is not hosted by an intermediary site. If you go too far up the chain, however, it may take quite some time for the complaint to filter down to the correct person.