What is Clutter anyway?
Clutter analyzes how you process your emails and determines what is unimportant to you. It then moves unimportant emails automatically from your Inbox folder and places them into the Clutter folder. In theory, this should leave you with an emptier and distraction-free Inbox folder.
Basically, the Clutter folder is your “second-tier” Inbox folder containing emails that you usually ignore.
However, if you don't want Outlook to automatically separate your email into Clutter, you can turn it off.
How to Turn Off Clutter
Open email in a web browser.
Click on the cog in the Top right corner then select Mail from the Drop down list.
Now on the left hand side Expand mail by clicking the triangle beside it and locate the clutter item under Automatic Processing.
Un-check "Separate items identified as clutter".
Now click Save at the top of the Clutter setting box.
Emails should no longer be going into the Clutter box automatically. If you run into any problems, please submit a Help Desk ticket.