c# Sending emails with authentication. standard approach not working

Question

I am trying to send an email using the following very standard code. However, I get the error that follow...

MailMessage message = new MailMessage();

message.Sender = new MailAddress("[email protected]");
message.To.Add("[email protected]");
message.Subject = "test subject";
message.Body = "test body";

SmtpClient client = new SmtpClient();
client.Host = "mail.myhost.com";
//client.Port = 587;

NetworkCredential cred = new NetworkCredential();

cred.UserName = "[email protected]";
cred.Password = "correct password";
cred.Domain = "mail.myhost.com";
client.Credentials = cred;
client.UseDefaultCredentials = false;     

client.Send(message);

---

Mailbox unavailable. The server response was: No such user here.

This recipient email address definitely works. To make this account work I had to do some special steps in outlook. Specifically, I had to do change account settings -> more settings -> outgoing server -> my outgoing server requires authentication & use same settings. I am wondering if there is some other strategy.

I think the key here is that my host is Server Intellect and I know that some people on here use them so hopefully someone else has been able to get through this. I did talk to support but they said with coding issues I am on my own :o

Answer 1

there is no mailbox called [email protected] on server mail.myhost.com, check that

Answer 2

try this...

NetworkCredential cred = new NetworkCredential(); 

cred.UserName = "[email protected]"; 
cred.Password = "correct password"; 
//cred.Domain = "mail.myhost.com"; 

... you should not need to provide the .Domain unless you are using Kerberos or some other complex authentication.

Edit...

Check out my extended answer. It has an example of how to send an email with authentication. It's also has SSL enabled so you may need to remove that part.