Error message: "The SMTP server requires a secure connection or the client was not authenticated." - smtpclient

Question

I have searched other posts and set required things in my gmail account(https://myaccount.google.com/lesssecureapps)
but somehow it still throws exception with the message "The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required. Learn more at"
[HttpPost]
public ActionResult SaveAppointment(Appointment mdl)
{
try
{
SmtpClient smtpClient = new SmtpClient("smtp.gmail.com", 587);
smtpClient.Credentials = new System.Net.NetworkCredential("username", "mypass");
smtpClient.UseDefaultCredentials = false;
smtpClient.DeliveryMethod = SmtpDeliveryMethod.Network;
smtpClient.EnableSsl = true;
MailMessage mail = new MailMessage();
//Setting From , To and CC
mail.From = new MailAddress("username#gmail.com", "MyWeb Site");
mail.To.Add(new MailAddress("username#gmail.com"));
smtpClient.Send(mail);
return View();
}
catch(Exception ex)
{
return null;
}
}
What should it be I missing?

Answer 1

Check your web.config, msdn and code (because there could be no matching EnableSsl in the configuration file.
You may also need to enable access for "less secure apps" in your gmail settings page. here
This is necessary if you are getting the exception "`The server response was: 5.5.1 Authentication Required. Then below code should works.
var client = new SmtpClient("smtp.gmail.com", 587)
{
Credentials = new NetworkCredential("username", "password"),
EnableSsl = true
};
client.Send("username#gmail.com", "username#gmail.com", "subject", "body");