Private Sub btnOutlook_Click(ByVal sender As Object, _
                               ByVal e As System.EventArgs) _
                               Handles btnOutlook.Click
    btnNeu.Text = "Änderungen &speichern"
    Editieren(True)
 
    Dim olApp As New Microsoft.Office.Interop.Outlook.Application
    Dim UrlOrdner As MAPIFolder
    UrlOrdner = olApp.GetNamespace("MAPI") _
                .Folders.Item("Öffentliche Ordner") _
                .Folders.Item("Alle Öffentlichen Ordner") _
                .Folders.Item("<NAMEDERFIRMA") _
                .Folders.Item("Verkauf") _
                .Folders.Item("Urlaub Logistik")
 
    Dim appItem As AppointmentItem = olApp.CreateItem( _
      OlItemType.olAppointmentItem)
    appItem.Subject = "Urlaub Test"
    appItem.Start = "06.10.2011 10:00"
    appItem.End = "07.10.2011 23:59"
    UrlOrdner.Items.Add(appItem)
 
  End Sub

UrlOrdner.Items.Add(appItem)