Precautions while using Social Networking Sites
To avoid giving away email addresses of your friends
To avoid giving away email addresses of your friends, do not allow social networking services to scan your email address book.When you join a new social network, you might receive an offer to enter your email address and password to find out if your contacts are on the network. The site might use this information to send email messages to everyone in your contact list or even everyone youve ever sent an email message to with that email address. Social networking sites should explain that theyre going to do this, but some do not.