The action that automatically moves email to the Clutter folder can be disabled by

1. Log into the web version of Outlook 
2. Click the gear icon in the top right corner.
3. Go to MAIL -> Message List -> Focused Inbox and uncheck the box and the hit "Save" in the bottom right corner. Now you can see all your mail.
4. If you don't like how every mail is in one place, you can repeat step 3 and check the box back on. Your mail will now be separated between "Focused" and "Other".