1. Sign in to the Office 365 Admin Center.
  2. Click on the Admin link at the bottom of the menu, then Exchange. This opens up the Exchange Control Panel, or ECP.
  3. In Exchange Control Panel, select Recipients > Resources.
  4. Click the + to create a new resource mailbox. You can select either a Room mailbox, or an Equipment mailbox.
  5. In the Room name, Location, Phone and Capacity fields, and hit save. The resource will now be created.

Making Changes

  1. You can edit the Mailbox by highlighting it, then clicking the Pencil symbol above to edit the Resource Mailbox.
  2. Booking Delegates: You can have booking requests accept or decline automatically, based on other settings, then first-come, first-served basis. Otherwise, you can select delegates are a user responsible for approving requests to book the resource. If you assign more than one delegate, only one needs to approve or deny a specific meeting request. Use the + symbol to add a delegate, or highlight an existing delegate and click the - symbol to remove the delegate.
  3. Booking Options:  This section gives you various options including maximum booking lead time, or and maximim booking length in hours.
  4. Contact Information: Fill in the various information about the resource here.
  5. Email Address: You generally should not need to add any addresses here.
  6. Mail Tip: You can set a message here to display to those booking the resource. It could contain response times or who can approve requests. 
  7. Mailbox Delegation: You should not need to set anything here - leaving as default is strongly suggested. 
  8. When you are finished, click Save.

Note: Sometimes, when creating a new resource mailbox and assigning delegates, you may get an error if the system has not had time to actually create the mailbox. If you get error messages about delegates or delegates aren't added, wait 24 hours and try again.

Additional reference: