PeopleSmart and Email Sherlock both offer free reverse email lookup. To search, a user enters the email address he wishes to look up, and the sites return information such as name, address, social networks and current phone number.
A reverse email lookup allows an individual to find out who owns a particular email address. Lookup services use such resources as email addresses associated with social media accounts to link email addresses to their owner's names and online and offline contact information. Results may also show the account owner's IP address and provide a map showing where his physicial mailing address is located.