The promotional email for the .Mac webmail refresh that went out over the weekend might have been a bit more revealing than we originally thought. Reader Harry noticed the address Apple used to send it was a bit different than the standard 'email@example.com' (and honestly, I'm signed up for so much promo stuff these days I don't pay attention to who it's from with stuff like this anymore). The email was sent from an inside.apple.com domain, and following it redirects you to an apple.com/chatterbox 'we'll be back soon!' maintenance page - not the typical 'Looking for something at Apple?' page.
Some googling revealed that others have seen this /chatterbox/ link used before, especially with images that are linked in newsletters, so this might be nothing more than some internal system for site and/or email and newsletter management. The 'we'll be back soon' bit simply makes it a little more interesting, as that sounds like it could actually be something public. In all likelihood it's nothing, and you can simply move along.