如何从SMTP服务器发送电子邮件？

Question

Hello I have a hosted Windows Server 2008 R2 Enterprise and a purchased domain name. I have pointed everything on my domain to my server's dns and uploaded my ASP.Net site to the IIS. I have also set up an SMTP Feature so now I'm trying to send emails from my SMTP but I can't because the application says that the user is not authenticated. Here is the source code of my page:

MailMessage activationMail = new MailMessage();
                activationMail.From = new MailAddress("no-reply@mydomain.com", "MyGame");
                activationMail.To.Add(RegistrationEmail.Text);
                StreamReader sRead = new StreamReader(Server.MapPath("~/Mails/ActivationMail.html"));
                string readFile = sRead.ReadToEnd();
                string Strcontent = "";
                Strcontent = readFile;
                Strcontent = Strcontent.Replace("[Name]", RegistrationRealName.Text);
                Strcontent = Strcontent.Replace("[Username]", RegistrationUsername.Text);
                Strcontent = Strcontent.Replace("[Password]", RegistrationPasswordCreate.Text);
                Strcontent = Strcontent.Replace("[useractivation]", useractivation);
                Strcontent = Strcontent.Replace("[Site]", site);
                Strcontent = Strcontent.Replace("[Facebook]", "facebook");
                activationMail.Subject = "My Game - Registration";
                activationMail.Body = Strcontent.ToString();
                sRead.Close();
                activationMail.IsBodyHtml = true;
                activationMail.BodyEncoding = UTF8Encoding.UTF8;
                SmtpClient client = new SmtpClient();
                client.Host = "mydomain"; 
                NetworkCredential cr = new NetworkCredential();
                cr.UserName = "User from AD DS";
                cr.Password = "Password of User";
                client.UseDefaultCredentials = false;
                client.DeliveryMethod = SmtpDeliveryMethod.Network;
                client.Port = 25;
                client.Timeout = 10000;
                client.Send(activationMail);

Note: My domain name is not the same with my forest's domain. I have also tried to set my forest's domain as the client.Host but same result. I have these settings on my Web.config

    <mailSettings>
      <smtp from="no-reply@mydomain">
          <network defaultCredentials="false" host="localhost" />
      </smtp>
  </mailSettings>

My SMTP server's settings are these:

• IP Address = My server's IP
• Authentication = Standar & Windows authentication are checked, TSL is checked, Default domain is set to my domain (not my MX record mail.domain). Anonymous authentication is not checked.
• Connection = Only my server's IP has access
• Relay = Only my purchased domain (not MX record) has access
• Outbound security = Standar authentication (User from AD DS - same credentials with the ones at my cs file above), TLS enabled
• Advanced delivery options = I set my domain name there (not MX record - gives me an error)

Does anybody know what am I doing wrong?

Answer 1

Add the following code as you haven't provided any credentials to the smtp:

client.Credentials = cr; 

Like:

 NetworkCredential cr = new NetworkCredential();
 cr.UserName = "User from AD DS";
 cr.Password = "Password of User";
 client.Credentials = cr; 
 client.UseDefaultCredentials = false;
 client.DeliveryMethod = SmtpDeliveryMethod.Network;
 client.Port = 25;
 client.Timeout = 10000;
 client.Send(activationMail);

Answer 2

try adding these two line:

client.EnableSsl = false;
client.Credentials = cr;