This is very impressive in itself but what is the practical use? I mean you probably could get (almost) the same result with much less work. For instance, "Acad

This is very impressive in itself but what is the practical use? I mean you probably could get (almost) the same result with much less work. For instance, "Academic" is every mail send from an .edu domain, "financial" is everything that comes from your bank, "personal" mails come from a sender that is in your personal address book and so on. In short, there are "good enough" rules that require much less processing.