The feature would not expose a user's email address until they reply to that email, but it sure would lead to an undesirable spam-like clutter in the Gmail inbox.
However, since the feature, which is to be rolled out in a couple of days, isn't as tough to undo, as it appears, users can simply 'opt-out' of it without much of a hassle.
According to Cnet, users can turn off the 'by default email via Google+ feature' by clicking on the Settings menu and under the General tab clicking on the said feature and choosing a setting they are most comfortable with.
Users can choose from options like 'Circles', 'Extended Circles' or 'No One' and save the changes to switch back the good old emailing sending feature.
--ANI (Posted on 11-01-2014)