Dropbox has announced plans to acquire the email app service company Mailbox, in a deal whose terms were not disclosed.

“Like many of you, when we discovered Mailbox we fell in love—it was simple, delightful, and beautifully engineered,” wrote Drew Houston and Arash Ferdowsi, the founders of Dropbox, on the company blog. ”Many have promised to help us with our overflowing inboxes, but the Mailbox team actually delivered.”

Dropbox will keep Mailbox as a stand alone app. The Wall Street Journal has more details: “Under the deal, the 13 employees of Mailbox owner Orchestra Inc.–including alums of Apple, Stanford University and Ideo–will join Dropbox.”

We included Mailbox on a list of five different iOS apps that can help your organize your email.