Just the other day Google announced that Gmail was getting a heavy dose of Google+ integration, and now, Google is adding that same functionality to Google Apps. This means that businesses who use Google as their email provider can be contacted using the "Email via Google+" button. However, admins must first enable this feature via the Admin panel, as they may prefer to prevent unnecessary emails from coming through the channel.
The feature was very controversial when first announced, as Gmail users were not thrilled with the prospect of people being able to email them without actually being given the email address. It's an even bigger deal for businesses, which is why Google is allowing admins to turn the feature off. In fact, Google promises that the feature will be off by default, which should come as music to the ears of any business that uses Google as its email service.
For page admins, controlling the feature is done via Google Apps, Gmail Settings, and then End User Settings. If the feature is on, the person emailing cannot see your email address unless you reply, nor can you see theirs.
Like the new contact method for regular users, if it is turned on by the admin, the default setting for each individual email address is for Anyone on Google+ to be able to contact you. This should certainly be the other way around, with users opting in to being contacted. If the Google Apps account you use has turned on the feature, you can opt out through the Email via Google+ option in settings. Check out this post for detailed instructions on disabling it. Of course, this is only applicable if your admin has opted into the program in the first place.
Source: TheNextWeb