Here is how:
Use a GUI based email client such as Outlook Express:
1. highlight that anonymous email
2. go to File, choose Properties
3. click on Details tab on the top
4. you will see a bunch of Received: from …
5. the LAST Received: from …(123.125.89.56, for example) has the IP of the computer where the email is originally sent. All other Received: from … are email relay servers.
6. if you feel excited to receive anonymous emails, I can send you thousands with fake sender names for you to enjoy. You email address is…?