smtp exception Failure sending mail?

Question

StringBuilder emailMessage = new StringBuilder();
emailMessage.Append("Dear Payment Team ,");
emailMessage.Append("<br><br>Please find the Payment instruction");    

try
{
    MailMessage Msg = new MailMessage();
    // Sender e-mail address.
    Msg.From = new MailAddress("[email protected]");
    // Recipient e-mail address.
    Msg.To.Add("[email protected]");
    Msg.CC.Add("[email protected]");
    Msg.Subject = "Timesheet Payment Instruction updated";
    Msg.IsBodyHtml = true;
    Msg.Body = emailMessage.ToString();
    SmtpClient smtp = new SmtpClient();
    //smtp.EnableSsl = true;

    smtp.Host = ConfigurationManager.AppSettings["HostName"];
    smtp.Port = int.Parse(ConfigurationManager.AppSettings["PortNumber"]);
    smtp.Send(Msg);
    Msg = null;
    Page.RegisterStartupScript("UserMsg", "<script>alert('Mail has been sent successfully.')</script>");
}
catch (Exception ex)
{
    Console.WriteLine("{0} Exception caught.", ex);
}

Added this code in web.config

<appSettings>
    <add key="HostName"   value="The host name as given by my company" />
    <add key="PortNumber" value="25" />
</appSettings>

I keep getting an exception tried changing the port number as specified but no success

Exception Detail

  System.Net.Mail.SmtpException was caught
  Message=Failure sending mail.
  Source=System
  StackTrace:
       at System.Net.Mail.SmtpClient.Send(MailMessage message)
       at PAYMENT_DTALinesfollowup.Sendbtn_Click(Object sender, EventArgs e) in d:\AFSS-TFS\AFSS\Code\ERPNET\PAYMENT\DTALinesfollowup.aspx.cs:line 488
  InnerException: System.Net.WebException
       Message=Unable to connect to the remote server
       Source=System
       StackTrace:
            at System.Net.ServicePoint.GetConnection(PooledStream PooledStream, Object owner, Boolean async, IPAddress& address, Socket& abortSocket, Socket& abortSocket6, Int32 timeout)
            at System.Net.PooledStream.Activate(Object owningObject, Boolean async, Int32 timeout, GeneralAsyncDelegate asyncCallback)
            at System.Net.PooledStream.Activate(Object owningObject, GeneralAsyncDelegate asyncCallback)
            at System.Net.ConnectionPool.GetConnection(Object owningObject, GeneralAsyncDelegate asyncCallback, Int32 creationTimeout)
            at System.Net.Mail.SmtpConnection.GetConnection(ServicePoint servicePoint)
            at System.Net.Mail.SmtpTransport.GetConnection(ServicePoint servicePoint)
            at System.Net.Mail.SmtpClient.GetConnection()
            at System.Net.Mail.SmtpClient.Send(MailMessage message)
       InnerException: System.Net.Sockets.SocketException
            Message=A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond 125.63.68.148:25
            Source=System
            ErrorCode=10060
            NativeErrorCode=10060
            StackTrace:
                 at System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress)
                 at System.Net.ServicePoint.ConnectSocketInternal(Boolean connectFailure, Socket s4, Socket s6, Socket& socket, IPAddress& address, ConnectSocketState state, IAsyncResult asyncResult, Int32 timeout, Exception& exception)
            InnerException: 

Answer 1

You need to give Username and password for smtp.

Use Below code :-

    MailSettings.SMTPServer = Convert.ToString(ConfigurationManager.AppSettings["HostName"]);
    MailMessage Msg = new MailMessage();
    // Sender e-mail address.
    Msg.From = new MailAddress("[email protected]");
    // Recipient e-mail address.
    Msg.To.Add("[email protected]");
    Msg.CC.Add("[email protected]");
    Msg.Subject = "Timesheet Payment Instruction updated";
    Msg.IsBodyHtml = true;
    Msg.Body = emailMessage.ToString();
    NetworkCredential loginInfo = new NetworkCredential(Convert.ToString(ConfigurationManager.AppSettings["UserName"]), Convert.ToString(ConfigurationManager.AppSettings["Password"])); // password for connection smtp if u dont have have then pass blank

    SmtpClient smtp = new SmtpClient();
    smtp.UseDefaultCredentials = true;
    smtp.Credentials = loginInfo;
    //smtp.EnableSsl = true;
    //No need for port
    //smtp.Host = ConfigurationManager.AppSettings["HostName"];
    //smtp.Port = int.Parse(ConfigurationManager.AppSettings["PortNumber"]);
     smtp.Send(Msg);

Answer 2

First, you don't need to manually read the values in your .config file. You can set the in the System.Net section and your SmtpClient object will read them automatically:

<system.net>
    <mailSettings>
      <smtp from="Sender's display name &lt;[email protected]&gt;">
        <network host="mailserver.yourdomain.com" port="25" userName="smtp_server_username" password="secret" defaultCredentials="false" />
      </smtp>
    </mailSettings>
  </system.net>

Then, from your code, you just write:

        SmtpClient smtp = new SmtpClient();
        MailMessage mailMessage = new MailMessage();
        mailMessage.To.Add(new MailAddress("[email protected]", "Recipient Display Name"));
        mailMessage.Subject = "Some Subject";
        mailMessage.Body = "One gorgeous body";
        smtp.Send(mailMessage);

Coming back to your error, it would appear you have some kind of a network problem.