Tracing the email sender [Yahoo]

In this post,I want to teach you how to trace the email sender.
In your mail,click the full header link in bottom right.



Then,look at the X-Originating-IP.
Go to http://www.arin.net/whois/
Paste the Ip adress in the query box.Click the Search Whois button.And you will get the sender's information.Note that the sender may spoof the indentitiy,making it's hard to get the real information.