title: .NET MailMessage DeliveryNotificationOptions stop working when adding a CC
body: <p>I recently added a CC to a .NET MailMessage. As soon as I did that the read return receipts stopped working. The read receipts are quite handy as they not only show who has read the message (provided the client supports it) but also the 'Deleted without being read' is useful feedback.</p>
  <pre><code>Using Msg As New MailMessage
  
              Msg.To.Add(New MailAddress(SendTo))
              Msg.From = New MailAddress(From)
              Msg.CC.Add(vCC)
              Msg.DeliveryNotificationOptions = DeliveryNotificationOptions.OnSuccess
              Msg.Subject = Subject
              Msg.Body = Body
              Msg.BodyEncoding = Encoding.GetEncoding(&quot;iso-8859-1&quot;)
              Dim AV As AlternateView = AlternateView.CreateAlternateViewFromString(Body, Nothing, &quot;Text/html&quot;)
              AV.TransferEncoding = Mime.TransferEncoding.QuotedPrintable
              Msg.AlternateViews.Add(AV)
              Try
                  Using vsmpt As New SmtpClient
                      vsmpt.Host = &quot;OurMailServer.net&quot;
                      vsmpt.Send(Msg)
                  End Using
                  Return True
              Catch ex As Exception
                  EmailError(ex)
                  Return False
              End Try
          End Using
  </code></pre>
  <p>Is there any reason for this strange behaviour?</p>
  <p>Thanks</p>
  <p><a href="https://i.stack.imgur.com/wIA7w.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/wIA7w.png" alt="MailMessage" /></a></p>