Whenever 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 and this is how you do it.
Windows Live Mail
Log into your Windows Live Mail account with your username and password,Open the inbox. To display the headers, right click on the email message in the Inbox, and select View Source.
This will open up a new page with a detailed header content.
Now look for Received: from followed by IP address within square brackets
If you have multiple Received: from headers, eliminate the ones that have proxy.anyknownserver.com.
Log into your Gmail account with your username and password, Open up the mail. To display the email headers, Click on the Reply drop down box and select Show Original.
Look for Received: from followed by the IP address between square brackets [ ].
If you find more than one Received: from patterns, select the last one.
Log into your Yahoo! mail with your username and password, Click on Inbox or whichever folder you have stored your mail, Open the mail. If you do not see the headers above the mail message, your headers are not displayed. To display the headers, click on the drop down Standard Header box and select Full Header.
Look for Received: from followed by the IP address between square brackets [ ]. If there are many instances of Received: from with the IP address, select the IP address in the last pattern. If there are no instances of Received: from with the IP address, select the first IP address in X-Originating-IP.
I hope this post will help you finding the IP address of the sender, do let us know what you think by leaving a comment.