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:

Answer 2

Gmail requires you to use a secure connection. This can be set in your web.config like this:

<network host="smtp.gmail.com" enableSsl="true" ... /> 

OR

The SSL should be enable on the webserver as well. Refer following link

Enabling SSL on IIS 7.0