Google is constantly pushing Google+, and the latest move is something that many Gmail users are not going to like. Now it is possible for anyone who has you in their Google+ circles to send you an email regardless of whether they have your email address. Your email address is not shared unless you choose to send it to them, but this is still a feature that many people are going to be unhappy with.
The feature works in conjunction with Gmail’s tabs, and should you receive a messaged from someone you do not have in your circles, the message will be demoted to the Social tab. In the case of people you do have in your circles, messages will appear in your inbox instead.
Thankfully, it is possible to change your account settings so this option is hidden from other Google+ users — it can be tailored so you will only receive messages from close contacts, or you can stop people from emailing your via your Google+ account entirely.
Head over to the Gmail website and click the gear icon to the upper right hand corner of the page before selecting the Settings option from the dropdown menu.
Make sure you are on the General tab and scroll down to the Email via Google+ section. Click the dropdown menu and select who you would like to be able to email you through your Google+ account. You can limit it to people in your extended circles, circles, or block everyone from sending you a message in this way. Of course you can also leave things so anyone is able to contact you in this way.
Scroll down to the bottom of the page and click the Save Changes button. That’s all there is to it!