This is a cool new feature coming soon between Google+ and Gmail. You may call this Google+ messaging through Gmail.
Let’s say you want to email someone in your Google+ circle but don’t know their email address. Previously you may me able to do this by Writing an Google+ post and share with the person you want to talk to. But the problem is the post may get lost in the stream among other posts (although he may get a notification about mention of you in the post). Now with this update you may achieve similar functionality within Gmail if you both are connected through Google+ and use Gmail.
If you both are connected through Google+, this email will get delivered to his primary inbox tab and when not connected it’ll show up in his social tab.
To use this feature, All you have to do is start typing your email (in Gmail) as you would normally do and instead of typing users email just type their name and Gmail will show contact suggestions from Google+ as well. Ofcourse they’ll appear separately than from your contact address book (refer image below).
Worried about message spamming? No worries, Gmail took care of that with a special setting that allows to opt-out and have full control over this feature.
Look for setting “Email via Google+: Who can email you via your Google+ profile with options: ‘Anyone on Google+’, ‘Extended circles’, ‘Circles’ or ‘No one’ [i.e completely disable it]”
This update has just been announced and might take couple of days before we all see it. We’ll share more details once we get a chance to try it out. Enjoy!