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

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C#

SmtpClient

I am trying to send an email in asp.net
i am accessing smpt ,username...atc parameters from web.config file.
my all credentials are correct but each time i get this error.

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


my code is this

private void SendHtmlFormattedEmail(string recepientEmail, string subject, string body)
        {
            try
            {
                using (System.Net.Mail.MailMessage mailMessage = new System.Net.Mail.MailMessage())
                {
                    Configuration config = WebConfigurationManager.OpenWebConfiguration(HttpContext.Current.Request.ApplicationPath);
                    MailSettingsSectionGroup mailSettings = (MailSettingsSectionGroup)config.GetSectionGroup("system.net/mailSettings");

                    mailMessage.From = new MailAddress(mailSettings.Smtp.From);
                    mailMessage.Subject = subject;
                    mailMessage.Body = body;
                    mailMessage.IsBodyHtml = true;
                    mailMessage.To.Add(new MailAddress(recepientEmail));
                    SmtpClient smtp = new SmtpClient();
                    smtp.Host = mailSettings.Smtp.Network.Host;
                    smtp.EnableSsl = mailSettings.Smtp.Network.EnableSsl;
                    System.Net.NetworkCredential NetworkCred = new System.Net.NetworkCredential();
                    NetworkCred.UserName = mailSettings.Smtp.Network.UserName;
                    NetworkCred.Password = mailSettings.Smtp.Network.Password;
                    smtp.UseDefaultCredentials = true;
                    smtp.Credentials = NetworkCred;
                    smtp.Port = mailSettings.Smtp.Network.Port;
                    smtp.Send(mailMessage);
                    
                }
            }

in config file

<system.net>
    <mailsettings>
      <smtp deliverymethod="Network" from="pearlcontinentalhb@gmail.com">
        <network host="smtp.gmail.com" username="Pearl Continental Hotel ,Bhurban" password="pchb" port="587" enablessl="true" />
      </smtp>
    </mailsettings>
  </system.net>