They paid a pretty penny too, $100 million to acquire Mailbox. As per the article from Wired (https://www.wired.com/2015/12/dropbox-kills-carousel-and-mailbox-a

They paid a pretty penny too, $100 million to acquire Mailbox. As per the article from Wired (https://www.wired.com/2015/12/dropbox-kills-carousel-and-mailbox-as-it-turns-toward-businesses/ https://www.wired.com/2015/12/dropbox-kills-carousel-and-mai...) they said: Although Mailbox could presumably fit into that strategy, Dropbox is instead focusing on its new Google Docs-style document editing and collaboration service Paper, which may gain some of the functionality of Mailbox. "As we deepened our focus on collaboration, we realized there’s only so much an email app can do to fundamentally fix email," a blog post credited to "the Mailbox team" reads. "We’ve come to believe that the best way for us to improve people’s productivity going forward is to streamline the workflows that generate so much email in the first place."