The new feature of Google allows you to send email to any Google + accounts without knowing their email according to David Nachum post, Google Product Manager.

"Have you ever started typing an email to someone only to realize halfway through the draft that you haven't actually exchanged email addresses? If you are nodding your head 'yes' and already have a Google+ profile, then you're in luck, because now it's easier for people using Gmail and Google+ to connect over email", David Nachum wrote in the official Gmail blog.

Users of the internet giant Google started the feature Thursday and raises concerns and criticized by some privacy advocates.

However, there is the "opt-out" option to give the Google + user the choice to share their email address.

Google says your address or that person's address is not visible to you unless they send you an email and you reply.

Selecting "No one" will not allow you to use the new feature. The default options will not allow you to be contacted randomly.

If you prefer to be emailed by some, but not all Google + users, choose "Circles" for people you know or Extended Circles for people you know and your circle know.

 An email with information and a link to the settings will be mailed by Google to all the users when the feature is available.

Recently, Google also rolled out a mandatory feature for users where they should log their Google+ Id to be able to post a comment on YouTube. This feature also raises criticism to those who do not have the said ID.

There will be exception for the celebrities on Google+, who are tag on by a large number of followers. These accounts made for public purposes, will not received emails from randomly.