Find the Originating IP Address of a Received Email

If you want to find out where somebody you are emailing is located, you can use the headers in Mail to find out.

Step 1: Open up one of the emails you received from them.

Step 2: Hit Cmd-Shift-H or go to the View > Message > Long Headers menu item.

Step 3: You should see that the info by the "From", "To", "Subject", etc. has considerably changed. After the "To" header there should be a bunch of "Recieved" headers. Find the one with the earliest date stamp. Copy the IP address associated with it. (The number in the brackets after "from" and before "by".

Step 4: Plug this number into an IP address geo-locator.