The SMTP server requires a secure connection or the client was not authenticated

Question

I am getting this error

The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.0 Must issue a STARTTLS command first. e17sm974159fak.34 

Web.config

<mailSettings>     <smtp deliveryMethod="Network"                 from="[email protected]">         <network defaultCredentials="false" host="smtp.gmail.com" port="587"                     userName="[email protected]"  password="12345678" />     </smtp>         </mailSettings> 

Code file

public void Submit()         {             EnsureCurrentlyValid();             // Send via email             var message = new StringBuilder();             message.AppendFormat("Date: {0:yyyy-MM-dd hh:mm}\n", DateTime.Now);             message.AppendFormat("Email from: {0}\n", Name);             message.AppendFormat("Email: {0}\n", Email);             message.AppendFormat("Message: {0}\n", Message);             SmtpClient smtpClient = new SmtpClient();             MailMessage m = new MailMessage(                 "[email protected]", // From                 "[email protected]", // To                 "Suggestion/Comments", // Subject                 message.ToString()); // Body              smtpClient.Send(m);         } 

Answer 1

Try setting the EnableSsl property to true:

smtpClient.EnableSsl = true; 

AFAIK this property can only be set in code and cannot be specified in the config file.