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Simply login to Outlook Web Access from any web browser (https://outlook.office.com) using your Hopkins credentials (JHED_ID@jh.edu)
Highlight (select) the spam message in your Inbox (or Deleted Items if you have already deleted it)
Click the small Down-Arrow under the "Forward" button and choose "Forward as attachment" (See screenshot below)
Address the message to spam@jhu.edu and send
Delete original spam message
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If you need further assistance reporting a spam message, please contact the SON Help Desk.