MailMessage m = new MailMessage
  ("item@jb51.net",
  "raja@jb51.net",
  "This is the subject for the authorized email.",
  "This is the body of the authorized mail!...");
// Send the message using authorization
SmtpClient client = new SmtpClient("smtp.jb51.net");
client.Credentials = new NetworkCredential("user", "password");
client.EnableSsl = true;
// Add the event handler
client.SendCompleted += new SendCompletedEventHandler(mail_SendCompleted);
// Send the message asynchronously
client.SendAsync(m, null);
// To Cancel the send
//client.SendAsyncCancel();
void mail_SendCompleted(object sender, AsyncCompletedEventArgs e)
{
  if (e.Cancelled)
    Console.WriteLine("Message cancelled");
  else if (e.Error != null)
    Console.WriteLine("Error: " + e.Error.ToString());
  else
    Console.WriteLine("Message sent");
}