Description: Use the function to report/mark suspicious email with malicious intent or classify an email as junk or spam.
Desktop Outlook Application
Step 1: Select an Email
Step 2: At the Top (Far Right) Navigational Options > Report Message
Step 3: Select one of the three options and note that Junk is also use to report Spam.
Office 365 Email (Web Interface)
Step 1: Select an Email and have it open in the reader pane.
Step 2: Select Junk from the navigational options