1. When you open the e-mail you could see a small down arrow button next to Reply button. Just click that to get some options listed.
2. Click the option Show Original which is the second from the bottom. A pop up will open in a new tab/window with some encoding information.
3. Take a close look at the encoded information, you will find the heading Received, look carefully you would find the name of the sender along with his / her IP address.
