1. Open up the Outlook web app by going to https://outlook.office.com/
  2. Click on your profile picture in the top right hand corner
  3. Click Open another mailbox
  4. Type the name of the shared mailbox and then click on the one you want to open
  5. The Shared mailbox will open in a new tab
  6. Click the settings cog in the top right of the new page
  7. Type Automatic in the search bar and click on Automatic Replies
  8. Turn on Automatic Replies by clicking the slider
  9. Fill in the desired information that you want sent as an automatic reply for both inside the organization and outside the organization.
  10. Click Save