How to Send EMail that receiver can't reply

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As title. I am developing a system that is able to send email with attachments to members. I want the receivers can't reply the received email because the sender email address may be virtual , like some email that contains "this email is sent by the system automatically, please do not reply."
I want to build this function but I found it is hard without 3rd party components, and those are expensive. I've tried some sample codes, one of this is like the below:

C#

public string SendEMail(string From,string To,string Subject,string Content)
        {
            try
            {
                System.Net.Mail.MailMessage msg = new System.Net.Mail.MailMessage();
                msg.To.Add(To);
                msg.From = new MailAddress(From, From, System.Text.Encoding.UTF8);

                msg.Subject = Subject; 
                msg.SubjectEncoding = System.Text.Encoding.UTF8; 
                msg.Body = Content; 
                msg.BodyEncoding = System.Text.Encoding.UTF8; 
                msg.IsBodyHtml = false; 
                msg.Priority = MailPriority.Normal;

                SmtpClient client = new SmtpClient();
                //client.Credentials = new System.Net.NetworkCredential(SenderAddress, SenderPassword);
                client.Host = "localhost";
                //client.EnableSsl = true;

                client.Send(msg);
                return string.Empty;
            }
            catch (Exception ex)
            {
                return "Exception:" + ex.Message + "Stacktrace:" + ex.StackTrace;
            }
        }

But I got the "Send EMail fail." exception message while executing this code. How could I get it?

Posted 26-Nov-15 14:29pm

Momoko Asahina 708H

Updated 30-Nov-15 18:59pm

v3

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Comments

PIEBALDconsult 26-Nov-15 20:40pm

That's simple; .net has all you need. I refer you to the System.Net.Mail namespace in general and the MailMessage class specifically.

Momoko Asahina 708H 26-Nov-15 20:44pm

I knew, but I tried to use many sample codes and fails. May I have more details about this way?

PIEBALDconsult 26-Nov-15 20:47pm

It's been a while since I last did it. Perhaps you should use Improve question to add the code you tried and explain how it didn't work, etc.

PIEBALDconsult 26-Nov-15 21:07pm

Ah, OK, better. Is your localhost an SMTP server? If not, don't use it as the client.Host .

Momoko Asahina 708H 26-Nov-15 21:21pm

No, my system will run at normal desktop PC with Windows Desktop System.

Tadit Dash (ତଡିତ୍ କୁମାର ଦାଶ) 26-Nov-15 21:08pm

Your network credentials are not set. You have commented that out.

Momoko Asahina 708H 26-Nov-15 21:22pm

I know, but how can I get credentials if the sender address doesn't exist?

PIEBALDconsult 26-Nov-15 21:28pm

The system doesn't care about the sender address. A colleague and I used to send each other emails with humorous sender addresses.

As per the documentation: "the Credentials property will be used for the credentials when connecting to the server" -- it doesn't affect the email at all, it identifies you to the SMTP server.

I see, in my code...
cl.UseDefaultCredentials = true

BillWoodruff 26-Nov-15 21:52pm

A common solution to this is to register a special domain name, and to send mail from that domain. Consider:

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Dave Kreskowiak · Answer 1 · 2015-11-26T17:53:00

You have a few problems. First, you have no control over the mail server you're using unless you set one up yourself. This means you are at the mercy of the policies setup on the mail server you're using to send the emails. No, you can't do anything without one.

This means that if the owner of the mail server says that it will not send or forward an email without a sender address, you have to put one in. If the owner says that the email address MUST match the account that is sending the email, you MUST put your email address in the sender field.

Where I work, it's impossible to send and email without the sender address filled in. It doesn't have to be a valid account. It just has to be filled in.

Now that you've gotten your email onto the server that is sending your mail, you have no defeated those problems. Some servers will not even deliver an email if the sender is not filled in. So leaving the field blank may not work for all of your recipients.

The best method to do what you want is to just create an email address (it usually doesn't even have to exist!) that says "noreply@yourdomain.com" or something similar. If the user replies to the email, that's their problem, not yours. Their email will not be deliverable if the email account doesn't exist. At worst, it'll sit in the inbox of an account that nobody monitors and eventually be deleted by the server.