Contact scraping is the practice of obtaining access to a customer's e-mail

E-mail

Electronic mail, commonly known as email or e-mail, is a method of exchanging digital messages from an author to one or more recipients. Modern email operates across the Internet or other computer networks. Some early email systems required that the author and the recipient both be online at the...

 account in order to retrieve contact information that is then used for marketing purposes.

The New York Times refers to the practices of tagged.com

Tagged.com

Tagged is a social networking site based in San Francisco, California, United States, founded in 2004. Tagged allows members to browse the profiles of other members, play games, and share tags and virtual gifts. Tagged says it has 100 million members. , Quantcast reports Tagged monthly unique...

, mylife.com and desktopdating.net as "contact scraping".

Several commercial packages are available that implement contact scraping for their customers including ViralInviter, TrafficXplode, TheTsunamiEffect.