Today we are beginning the roll out of Clutter to Office 365 business customers, which brings the power of Office Graph to your inbox. Clutter is designed to help you focus on the most important messages in your inbox. It uses machine learning to de-clutter your inbox by moving lower priority messages out of your way and into a new Clutter folder. Ultimately, Clutter removes distractions so you can focus on what matters most.
Read more at source: http://blogs.office.com/2014/11/11/de-clutter-inbox-office-365/