Email notifications walk a fine line between useful and annoying. I find that I like receiving them for some services (Twitter, especially when I get a new follower or get retweeted or mentioned) and I absolutely hate receiving them for others (Foodspotting, Foursquare). It's just the nature of the thing. If you're someone who enjoys notifications, Google+ is hoping that their latest update to that system will improve your experience when they hit your inbox.
Now, Google+ and Gmail users will be able to add people to their circles from within Gmail. So if you get that email saying that John Q. Johnson added you to one of their circles, you can add them back with a couple of clicks.
We've made a small tweak that improves Circle notification messages in Gmail. From now on whenever someone adds you to a circle, you can add them back right from the Google+ notification email. Just mouse-over the "Add to Circle" button and pick the circles you want, or create a new circle. The button will show you if this person is already in your circles. Check it out and let us know what you think
From the email, you can even create a new circle in which to stash your new contact.
Way back in October, 2011, Google made an update to Google+ that allowed users to control the notification volume within Google+. Soon thereafter, Google tweaked Google+ to allow you to add people to circles straight from the notifications within Google+.
Add this functionality to email notifications should help people to be more vigilant when it comes to adding new people to circles. Before, if you simply received an email notification that somebody added you, you would have to immediately add them back by going to your Google+ notifications, otherwise you'd most likely forget.
Google+ has recently rolled out some updates to Hangouts as well, as two features, collaborative docs and free phone calls, have officially graduated from Google+ with Extras to become part of the core Hangout experience.