catch multiple file attachments from Groupwise in winforms vb.net

The code attached will process ONE file dragged from a Groupwise message on to a winforms ListBox.   What I need now is how to discover and process them if the user drags over several files from Groupwise at one time.

Dim ob As System.Object = Nothing
        Dim ms As System.IO.MemoryStream

        ms = e.Data.GetData("attachment format", True)
        Dim b(ms.Length) As Byte
        ms.Read(b, 0, b.Length)

        strfilename = System.Text.Encoding.Unicode.GetString(b)
        '//The path/filename is at position 10.

        strfilename = strfilename.Substring(10)

        strfilename = ctrl.GetLongPathName(strfilename)


        If strfilename.EndsWith("pdf", StringComparison.CurrentCultureIgnoreCase) Or _
           strfilename.EndsWith("gif", StringComparison.CurrentCultureIgnoreCase) Then
            e.Effect = DragDropEffects.Copy
        Else
            e.Effect = DragDropEffects.None
            ms.Close()
            Exit Sub
        End If

        If Not System.IO.File.Exists(strfilename) Then
            MsgBox("File not found")
        Else
            MsgBox("File was found")
        End If

        ms.Close()

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