...
If XL Is Nothing Then GL.set_XL
XL.Visible = True
For Each XW In XL.Workbooks
    If XW.FullName = "D:\temp\Beispiel.xls" Then
        Exit For
    End If
Next XW
If XW Is Nothing Then Set XW = XL.Workbooks.Open("D:\temp\Beispiel.xls")
XW.Activate
Set XS = XW.Worksheets("Tabelle 1")
XS.Activate
XS.Select
...

' Hier wird eine neue Spalte angehängt und gefüllt
i = XL.WorksheetFunction.CountA(XS.Columns(1)) + 1 
XS.Cells(i, 1) = mIt.ReceivedTime
XS.Cells(i, 2) = mIt.Subject
XS.Cells(i, 3) = mid(mIt.body,23,25)