Yesterday, Google introduced a feature to Gmail some might not be too happy about. By default, anyone with a Google+ account can now send an email to your Gmail account whether they have your address or not. As long as your name is attached to a Google+ and Gmail account, you can receive messages from strangers like the one seen above.
If that is something that doesn't sound appealing to you, don't worry, you can disable the feature and return your account to the legacy privacy settings. Google provides 4 different options under the Email via Google+ section, "Anyone on Google+", "Extended circles", "Circles" or "No one." The name of the settings more or less speak for themselves, with the "No one" effectively retuning your account back to its usual state and disabling the feature entirely.
To find these options login to your Gmail account, head to your settings page from the gear icon on the top right corner of the screen. Then in the General tab, scroll down to hit the pull down menu in the Email via Google+ section to view the options (don't forget to save your changes).
With the ability to turn it off, the Facebook like messaging really doesn't sound like a big problem for those that don't want strangers to send messages to their personal email accounts. Google says, the person contacting you can't actually see your email address unless you email them back.