OIT Home > OIT Knowledge Base Search Knowledge Base: How do I open a Resource Mailbox Room in Office 365? To open a Resource Mailbox Room in Office 365, please follow the instructions below. 1. Log into Office 365. 2. Select the app launcher grid in the upper left corner. 3. Choose Calendar. Note: if you do not see the calendar, choose All apps > Calendar. 4. Right-click on Your calendars and select Open calendar. Note: If you have your account set up in Outlook, you may use the Rooms heading instead of My Calendars. 5. Type the name of the Room in the From directory field and choose Search Directory. Select the Room and choose Open. Need more help?