Private Declare Function NetMessageBufferSend Lib "netapi32.dll" ( _
    lpServerName As Any, _
    lpMsgName As Byte, _
    lpFromName As Any, _
    lpBuf As Byte, _
    ByVal lnBufLen As Long _
) As Long
Private Const NERR_Success As Long = 0&
Public Function SendMsg(SendTo As String, SendBy As String, message As String) _
  As Long
    Dim WrittenTo() As Byte
    Dim MSGBuffer() As Byte
    Dim WrittenBy() As Byte
    'Anscheinend funktioniert das mit den neuen Sicherheitsupdates von 
    ' Microsoft nicht mehr.
 
    WrittenTo = SendTo & vbNullChar
    MSGBuffer = message & vbNullChar
    WrittenBy = SendBy & vbNullChar
 
    SendMsg = (NetMessageBufferSend(ByVal 0&, WrittenTo(0), _
    WrittenBy(0), MSGBuffer(0), UBound(MSGBuffer)) = NERR_Success)
 
End Function

Dim Result As Boolean
   Result = SendMsg("Empfänger", "Sender", "Text")
   End