Seleccione subcarpetas, si las hay: vb.net, Outlook, carpetas

Quiero verificar si existen subcarpetas, luego seleccionar esas subcarpetas.

Selecciono una carpeta con getDefaultfolder, me gusta:

" INBOX
siFolder = Ctype(ns.GetDefaultFolder(Outlook.OlDefaultFolders.olFolderInbox), Outlook.Folder)
" SENT ITEMS
siFolder = Ctype(ns.GetDefaultFolder(Outlook.OlDefaultFolders.olFolderSentMail), Outlook.Folder)
etc ...

Where ...
app = New Outlook.Application()
ns = app.Session

Funciona bien, pero no puedo ver si hay subcarpetas existentes y no sé cómo seleccionarlas.

Respuestas

 Private Sub  CreateNewFolder()
Dim oApp As Outlook.Application = New Outlook.Application
Dim oNS As Outlook.NameSpace = oApp.GetNamespace("MAPI")
Dim InboxFolder As Outlook.MAPIFolder = oNS.GetDefaultFolder(Outlook.OlDefaultFolders.olFolderInbox)
Dim customFolder As Outlook.MAPIFolder
Try
For i = 1 To InboxFolder.Folders.Count
If InboxFolder.Folders.Item(i).Name = "Vellaichamy" Then
Exit Sub
End If
Next
customFolder = InboxFolder.Folders.Add("Vellaichamy", Outlook _
.OlDefaultFolders.olFolderInbox)
InboxFolder.Folders("Vellaichamy").Display()
Catch ex As Exception
MessageBox.Show("The following error occurred: " & ex.Message)
Finally
" Clean up.
oApp = Nothing
oNS = Nothing
InboxFolder = Nothing
customFolder = Nothing
End Try
End Sub