In effort to allow you to reach people easier, Google+ will soon allow you to send anyone you’re connected to an email, even if you don’t know their address. Gmail will now suggest your connections from Google+ as potential recipients when composing a new email. The email app will also automatically sync with Google+ to keep your contacts up to date.
Google also mentioned that your email address is only shared with the people you want, as your address only becomes known if you send a person an email. And someone can only start another conversation with you if you have responded or added them to your circles.
You can also enable or disable this feature in a new Gmail setting. Google says this capability is rolling out over the next few days and that everyone will get an email with more information when the new feature goes live.
On the Gmail blog Google said:
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.