c# - The server response was: 5.7.0 Must issue a STARTTLS command first. i16sm1806350pag.18 - gsmtp

Question

I am trying to send mail using gmail, and I am getting an exception that is 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. i16sm1806350pag.18 - gsmtp

code I have written for sending mail is:

MailMessage mail = new MailMessage(); 
mail.To.Add(txtEmail.Text.Trim()); 
mail.To.Add("[email protected]");
mail.From = new MailAddress("[email protected]");
mail.Subject = "Confirmation of Registration on Job Junction.";
string Body = "Hi, this mail is to test sending mail using Gmail in ASP.NET";
mail.Body = Body;
mail.IsBodyHtml = true;
SmtpClient smtp = new SmtpClient("smtp.gmail.com", 587);
// smtp.Host = "smtp.gmail.com"; //Or Your SMTP Server Address
smtp.Credentials = new System.Net.NetworkCredential("[email protected]", "password");
// smtp.Port = 587;
//Or your Smtp Email ID and Password
smtp.UseDefaultCredentials = false;
// smtp.EnableSsl = true;
smtp.Send(mail);

Please tell me solutions, I am not getting any solutions for this exception.

Answer 1

Step (1): smtp.EnableSsl = true;

if not enough:

Step (2): "Access for less secure apps" must be enabled for the Gmail account used by the NetworkCredential using google's settings page: