How to initialize mailbox in dialog using displaydialogAsync

In my Office Add-in for Outlook, I am launching a new dialog window in my react app using Office.context.ui.displayDialogAsync. This launches the new window and a new instance of my app as expected. In this new instance, Office.context appears to be initialized; however, Office.context.mailbox is undefined. Is there any way to load this new window with an instance of Office.context.mailbox?