The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required
c#
Solution
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Problem
I have a Problem, when i m sending a mail through this code then error is occured that "The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required. " and my code is : ``` protected void ImageButton1_Click(object sender, ImageClickEventArgs e) { MailMessage mail = new MailMessage(); mail.To.Add("info@msslindia.com"); mail.From = new MailAddress("info@msslindia.com"); string body = "<table><tr><td>Company Name:</td><td>" + txt_cname.Text + "</td></tr><tr><td>Address With No.:</td><td>" + txt_addwithno.Text + "</td></tr><tr><td>Contact Person:</td><td>" + txt_conperson.Text + "</td></tr><tr><td>Email Id</td><td>" + txt_email.Text + "</td></tr><tr><td>Description</td><td>" + txt_description.Text + "</td></tr></table>"; mail.Body = body; mail.IsBodyHtml = true; SmtpClient smtp = new SmtpClient(); smtp.Host = "smtp.gmail.com"; smtp.Port = 25; smtp.UseDefaultCredentials = true; smtp.Credentials = new System.Net.NetworkCredential("info@msslindia.com", "xyz"); smtp.EnableSsl = true; smtp.Send(mail); txt_cname.Focus(); txt_cname.Text = ""; txt_addwithno.Text = ""; txt_conperson.Text = ""; txt_email.Text = ""; txt_description.Text = ""; } ```