Actually, I want to ask a question about encryption but when I saw this discussion and since I am a German, I want to share my opinion.
I don't agree that "Gemeinsamer Ordner" is a nice term for smart inbox.
It does not describe the overall function of this box.
And by the way, "unified" does not mean "gemeinsam" but "einheitlich".
The last suggestion from Freak is not too bad. "Fokus" describes exactely the function, for this box contains the mails which are currently in the focus of interest.
Moreover the name is not that long. In my view, a nice term would be "Fokusbox".