smtp.send method throws exception

Question

I am using .net version 3.5 for sending mails though my web application

I get the following error:

The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.1 Client was not authenticated

What could be causing this?

Answer 1

Source from here http://www.systemnetmail.com/faq/4.2.aspx

//create the mail message
MailMessage mail = new MailMessage();

//set the addresses
mail.From = new MailAddress("me@mycompany.com");
mail.To.Add("you@yourcompany.com");

//set the content
mail.Subject = "This is an email";
mail.Body = "this is the body content of the email.";

//send the message
SmtpClient smtp = new SmtpClient("127.0.0.1");

//to authenticate we set the username and password properites on the SmtpClient
smtp.Credentials = new NetworkCredential("username", "secret"); 
smtp.Send(mail);

EDIT: This error means what it's written: smtp server needs authentication information (username and password). So, you need set SmtpClient.Credentials.

Answer 2

Try:

smtpclient.EnableSsl = true;

Answer 3

The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.1 Client was not authenticated

so you need to authenticate by adding credentials

smtpClient.Credentials = new NetworkCredential("username", "password");