Edit: After half day, my wife’s Mac started having the same problem. I have then applied the solution that I found in the Apple
Dropbox Acquires Popular Email App Mailbox
Dropbox has just announced via its website that the company has just acquired the popular iOS email app Mailbox. The popular mail application hit the App store around a month ago and saw great demand.
Mailbox CEO said today
“Rather than grow Mailbox on our own, we’ve decided to join forces with Dropbox and build it out together”
From what is being said in the blog post it appears this deal was done to allow Mailbox to keep up with the demand for the product. It is still unknown what Dropbox had to pay for such an app which is as high demand as Mailbox but we will update this article if we here anything.
Regarding the staff, 13 members of the Mailbox team will join forces with Dropbox to help development of the product.
You can find the full blog post here