EWS and Unread Mail SearchFolder

I've been able to find searchfolders for my mailbox using EWS with ExchangeVersion.Exchange2007_SP1 and the following FindFolders call:

FindFoldersResults folderItems = service.FindFolders(WellKnownFolderName.Root, new FolderView(int.MaxValue) { Traversal = FolderTraversal.Deep });

The SearchFolders that are returned are: Reminders, Spooler Queue, To-Do Search - none of which appear in my outlook client.  On my Outlook client, I can see the following SearchFolders: Categorized Mail, For Follow Up, Large Mail, Unread Mail - however, these don't show up in the FindFoldersResults from the FindFolders call.

How can I get the Unread Mail SearchFolder view using EWS?

Andy