Possibly. At the same time, Mailbox supports iCloud and gMail. They say SlideMail is different in that it is not for power users. So non-power-users that have t

Possibly. At the same time, Mailbox supports iCloud and gMail. They say SlideMail is different in that it is not for power users. So non-power-users that have their own email server or don't use gMail/iCloud? Maybe people that don't want Dropbox to have access to your email, which is fair. In which case, push privacy as a differentiator. But that isn't nearly as sexy or mass-market as personalization; I think many average users have gotten used to their online information being own by someone else.