IPNetInfo is a neat little FREE tool that allows users to retrieve all of the available information about an IP address. Important information including the owner of the IP address, country and state, IP address range, contact information (address, phone, fax, email) and more. This tool can also prove useful for finding the origin of unsolicited mail. Simply copy the message headers from your email software and paste them into the IPNetInfo tool. IPNetInfo will then extract all IP addresses from the message headers, and display the information about these IP addresses.
Authors Website: nirsoft.net/utils/ipnetinfo.html
Download: You can download IPNetinfo HERE