Gmail and Google+ Integration - Everything you need to know, Explained and Simplified:
Can I really send an email to anyone on Google Plus?
*1 You can send emails to anyone on Google Plus as long as they are in your circles. And since you can add anyone on Google+ to your circles - you can send emails to anyone on Google+.
Does that mean I can see their email address?
*2 When you send an email to a Google+ user through Gmail, you will only see his name and not his email (see the image below, under Google+ Connections). The only way you will be able to see his email address is if he decides to reply to your email.
Can I send multiple emails to a certain Google+ user?
*3 You can send only 1 email to each Google+ contact in your circles. Only if that contact decides to reply to your email, you will
*4 As you can see in the example image above, people from you Google+ circles will be indicated under the Google+ Connections bar.
I'm not interested in this feature. Can I turn it off?
*5 You can easily opt out of this feature. Simply Go Here and scroll down to where it said Email via Google+. You can change the settings from "Anyone on Google+", to "Extended Circles" or "Circles". After you choose you settings, click save at the bottom of the page.
Do you like this new feature? Yes? No? Share your thoughts in the comment section below!
Official Gmail Blog Post: Reach the people you know more easily