Note: Also see Report A Message as Spam/Phishing using Outlook Desktop App
For messages in the Inbox or any other email folder except Junk Email, use either of the following methods to report spam and phishing messages:
Select the message, click Junk on the toolbar, and then select Junk or Phishing.
Select one or more messages, right-click, and then select Mark as junk.
In the dialog that appears, click Report. If you change your mind, click Don't Report.
The selected messages will be sent to Microsoft for analysis. To confirm that the messages have been submitted, open your Sent Items folder to view the submitted messages.