The free app, which smartly integrates a calendar and file picker to help you power through your messages, is one of the best mobile email solutions for users of Microsoft Exchange. The app is also debuting its take on Googles priority inbox today, with a new feature it calls focused inbox. Acompli users spend only around 22 seconds in the app per session, founder Javier Soltero says, and focused inbox is a way of trying to make those seconds as productive as possible.