How to find ip address of email sender of yahoo mail or gmail?

Looking at the mail headers, you can see who sent it and the host IP, but sender IP addresses aren't included in the header.

There is a technique that sometimes works, and it's a well-known trick used by spammers. Reply to the email with an HTML email that includes an image hosted by a server you control, with a unique query string in the URL. If the person opens the email AND displays images, your image will load. You can see which IP address loaded the image, and match that with the email address where you sent the image. Of course, even if this works it will give you the IP address where they read your message, not the one from which they sent the first email. This trick is the main reason that email programs check before they load images now. You could also sue them, get a subpeona and force Google or Yahoo to get the IP address from their logs. Or you could just hack into their systems and find out yourself.

You need to look into the mail header which is where you can find the ip address. Edit: Funny that this was the correct answer but was the only one that got a negative vote. You can go to this link to find out more http://aruljohn.com/info/howtofindipaddress/#gmail and to use some scripts that will make it easier for you. But in short, the IP address can usually be found in the header. Reading the header is different for every email provider so you will have to read to find out how. Some email services such as Google will never share the sender IP. But I've heard that if a sender uses a mail client such as Thunderbird, that the IP can always be tracked, haven't tested it yet though. Good luck!