Over the next few days we’ll be rolling out a new feature that will suggest users’ Google+ connections as recipients, along with their traditional Gmail contacts, when composing a new email. Your email address isn’t visible to a Google+ connection unless you send that person an email, and likewise, that person’s email address isn’t visible to you unless they send you an email. Importantly, if someone outside a your Google+ circles sends you an email this way, you can decide whether you want to receive more emails from that person.
Domain administrators will have the option to control the availability of this feature through a new setting in the Admin console under Google Apps-> Gmail Settings -> End User Settings. If this feature is enabled in the Admin console, users can control whether people outside their circles can reach them with a new setting in Gmail. They will be able to choose from Anyone on G+, Extended Circles, Your Circles and No one. The default setting will be ‘Anyone on Google+’.
Google Apps for Business, Education, and Government
For more information:
Reference by : http://www.google.com/