For my silverlight project I'm creating a newsletter which can be send through a certain page.
For this I have a newsletter service which can be seen here:
       public bool SendMail(string emailTo, string emailFrom, string msgSubject, string msgBody)
    {
        bool success = false;
        try
        {
            MailMessage msg = new MailMessage();
            msg.From = new MailAddress(emailFrom);
            msg.To.Add(new MailAddress(emailTo));
            msg.Subject = msgSubject;
            msg.Body = msgBody;
            msg.IsBodyHtml = true;
            SmtpClient smtp = new SmtpClient();
            smtp.Host = "smtp.gmail.com"; // Replace with your servers IP address
            smtp.Port = 465;
            smtp.EnableSsl = false;
            smtp.Send(msg);
            success = true;
        }
        catch(Exception e)
        {
            success = false;
        }
        return success;
    }
And I ask the service to send the mail with the following code:
   public partial class Nieuwsbrief : UserControl
{
    IEnumerable<Inschrijvingen> ingeschrevenen = null;
    public Nieuwsbrief()
    {
        InschrijvingenServiceClient personclient = new InschrijvingenServiceClient();
        personclient.getInschrijvingenCompleted += new EventHandler<getInschrijvingenCompletedEventArgs>(personclient_getInschrijvingenCompleted);
        personclient.getInschrijvingenAsync();
        InitializeComponent();
    }
    private void btnSubmit_Click(object sender, RoutedEventArgs e)
    {
        NieuwsbriefServiceClient client = new NieuwsbriefServiceClient();
        //foreach (Inschrijvingen person in ingeschrevenen)
        //{
            client.SendMailAsync("test@gmail.com", "nieuwsbrief@ondernemersaward.be", txtSubject.Text, txtContent.Text);
        //}
        client.SendMailCompleted += new EventHandler<SendMailCompletedEventArgs>(client_SendMailCompleted);
    }
    void personclient_getInschrijvingenCompleted(object sender, getInschrijvingenCompletedEventArgs e)
    {
        ingeschrevenen = e.Result;
    }
    void client_SendMailCompleted(object sender, SendMailCompletedEventArgs e)
    {
        if (e.Error != null)
            txtContent.Text = "Mail has NOT send!" + e.Error.ToString();
        else
            MessageBox.Show(e.Result.ToString());
    }
}
However when I press btnSubmit nothing happens, untill I shut down the server and then I get the following error: 
Mail has NOT send!System.ServiceModel.CommunicationException: The remote server returned an error: NotFound. ---> System.Net.WebException: The remote server returned an error: NotFound. ---> System.Net.WebException: The remote server returned an error: NotFound.
   at System.Net.Browser.ClientHttpWebRequest.InternalEndGetResponse(IAsyncResult asyncResult)
   at System.Net.Browser.ClientHttpWebRequest.<>c__DisplayClass5.<EndGetResponse>b__4(Object sendState)
   at System.Net.Browser.AsyncHelper.<>c__DisplayClass4.<BeginOnUI>b__0(Object sendState)
   --- End of inner exception stack trace ---
   at System.Net.Browser.AsyncHelper.BeginOnUI(SendOrPostCallback beginMethod, Object state)
   at System.Net.Browser.ClientHttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
   at System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelAsyncRequest.CompleteGetResponse(IAsyncResult result)
   --- End of inner exception stack trace ---
   at System.ServiceModel.AsyncResult.End[TAsyncResult](IAsyncResult result)
   at System.ServiceModel.Channels.ServiceChannel.EndCall(String action, Object[] outs, IAsyncResult result)
   at System.ServiceModel.ClientBase`1.ChannelBase`1.EndInvoke(String methodName, Object[] args, IAsyncResult result)
   at OndernemersAward.NieuwsbriefServiceReference.NieuwsbriefServiceClient.NieuwsbriefServiceClientChannel.EndSendMail(IAsyncResult result)
   at OndernemersAward.NieuwsbriefServiceReference.NieuwsbriefServiceClient.OndernemersAward.NieuwsbriefServiceReference.NieuwsbriefService.EndSendMail(IAsyncResult result)
   at OndernemersAward.NieuwsbriefServiceReference.NieuwsbriefServiceClient.OnEndSendMail(IAsyncResult result)
   at System.ServiceModel.ClientBase`1.OnAsyncCallCompleted(IAsyncResult result)
I hope somebody can help me, Thanks :)
 
    