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 STARTTL         


        

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.