Clutter is an Office 365 tool which moves your low priority messages out of your Inbox so you can easily scan for important messages. Clutter analyzes your email habits and based on your past behavior, it determines the messages that you’re most likely to ignore. It then moves those messages to a folder called Clutter, where you can review them later.
When your Office 365 account is created, Clutter is turned off, but it monitors your email reading and turns itself on after a couple of weeks. This may cause some mail to be removed from your Inbox. If you choose to turn Clutter off again, it will remain off.
Microsoft has documentation for using Clutter.View All FAQs in this Section