When you receive an email, you receive more than just the message. The email comes with headers that carry important information that can tell where the email was sent from and possibly who sent it. For that, you would need to find the IP address of the sender. The tutorial below can help you find the IP address of the sender. Note that this will not work if the sender uses anonymous proxy servers.
Finding IP address in Yahoo! Mail
1. Log into your Yahoo! mail with your username and password.
2. Click on Inbox or whichever folder you have stored your mail.
3. Open the mail.
4. If you do not see the headers above the mail message, your headers are not displayed. To display the headers,
* Click on Options on the top-right corner
* In the Mail Options page, click on General Preferences
* Scroll down to Messages where you have the Headers option
* Make sure that Show all headers on incoming messages is selected
* Click on the Save button
* Go back to the mails and open that mail.
5. You should see similar headers like this:Yahoo! headers : nameLook for Received: from followed by the IP address between square brackets [ ]. Here, it is 126.96.36.199.That is be the IP address of the sender!
6. Track the IP address of the sender