From the Mailbox homepage:
It’s with heavy hearts that we let you know we’ll be shutting down Mailbox on February 26, 2016.
… as we deepened our focus on collaboration, we realized there’s only so much an email app can do to fundamentally fix email. 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.
I wasn’t a Mailbox user myself but do feel sad for the people who bought into it and are now left on their own.
There is nothing wrong with apps being shutdown. Some companies do it to regain focus, others because the app itself didn’t find its market. However in this case you get the feeling Mailbox itself isn’t being shutdown because the app is a failure on its own, but because it’s not meeting the growth curve required to legitimize a foolish $10 billion evaluation of its owner Dropbox.
That’s what hurts the most I think, and it’s not the first time we’ve seen this. Large VC-funded company X buying up an upcoming app Y or studio Z just to fuel the unrealistic growth forecast of their VC owners. It’s not good for the user and it’s not good for long term innovation/competition.