The Clutter folder is Microsoft’s attempt to help filter out emails based on how you read (or don’t read) your emails. Click this link and scroll down to “How Clutter filters messages” for more information. In case you are curious, the Junk mail folder is based not on your behavior, but on whether or not it appears to Microsoft if the email in question is spam or an unwanted solicitation. One other thing to note, adding email addresses or domain names (i.e. @samford.edu) to IronPort, the university spam filter, will not affect whether or not an email lands in the Clutter folder.