title: Send mail in C# without Password - Send failure error
body: <p>I am trying to implement a functionality in C# for mail sending, 
  I <strong>tried with gmail settings and it worked fine</strong>.
  but my requirement is to do it without password for mail id from which we r sending mail, my settings are</p>
  
  <pre><code>MailMessage mailMessage = new MailMessage("abcd@abcd.com", "pqrs@pqrs.com");
  
  mailMessage.Subject = "Welcome";
  mailMessage.Body = "---- Mail Body ---";
  mailMessage.IsBodyHtml = true;
  SmtpClient smtp = new SmtpClient();
  smtp.Host = "000.000.000.000"; // we need to set a particular IP here
  smtp.EnableSsl = true;
  
  System.Net.NetworkCredential NetworkCred = new System.Net.NetworkCredential();
  NetworkCred.UserName = "abcd@abcd.com";
  NetworkCred.Password = "";
  smtp.UseDefaultCredentials = true;
  smtp.Credentials = NetworkCred;
  smtp.Port = "25";
  smtp.Send(mailMessage);
  </code></pre>
  
  <p>It fires an error 'Failure Sending Mail'.
  As per requirement we don't have password to the mail id, and SMTP port is an IP
  First time facing this situation and googled a lot for this but can't find a solution</p>
  
  <p>Please help  </p>