enviar emailes con asp.net

[.seb]

Código:

                System.Net.Mail.SmtpClient client = new System.Net.Mail.SmtpClient("relay-hosting.xxxxxxxxxxx.net",25);
                System.Net.Mail.MailAddress from = new System.Net.Mail.MailAddress("[email protected]");
                System.Net.Mail.MailAddress to = new System.Net.Mail.MailAddress("[email protected]");
                System.Net.Mail.MailMessage msg = new System.Net.Mail.MailMessage(from, to);
                msg.Subject = "Mail desde la pagina";
                msg.Body = "De:" + txtEmail.Text + ";" + System.Environment.NewLine;
                msg.Body += txtMensaje.Text;
                msg.BodyEncoding = System.Text.Encoding.UTF8;
                System.Net.NetworkCredential nc = new System.Net.NetworkCredential(System.Configuration.ConfigurationManager.AppSettings["mailUser"], System.Configuration.ConfigurationManager.AppSettings["mailPwd"]);
                client.Credentials = nc;
                client.Send(msg);