the SMTP server requires a secure connection or the client was not authenticated. The server response was 5.5.1, Authentication required

Question

I have been trying to get my application to send an email for over an hour now, and i've tried everything i've found online but i still get the exception mentioned in the title of my question.

Here is the code i used:

        SmtpClient client = new SmtpClient();
        client.Host = "smtp.gmail.com";
        client.Port = 587;
        client.Credentials = new NetworkCredential("Sender email", "Sender email password");
        client.EnableSsl = true;
        client.UseDefaultCredentials = false;
        client.DeliveryMethod = SmtpDeliveryMethod.Network;

        MailMessage mail = new MailMessage();
        mail.From = new MailAddress("Sender email", "Sender");
        mail.To.Add(new MailAddress("My email"));
        mail.Subject = "TEST";
        mail.IsBodyHtml = true;
        mail.Body = sb.ToString();

        client.Send(mail);

I have allowed access to less secure apps on my account. I have also tried enabling 2FA and then generating an application specific password, but the exception stays.

client.UseDefaultCredentials is set to false, as you can see in my code snippet, and in the actual code i did put the actual email and the password but for obvious reasons i removed those from the snippet. — chrisstar123, Aug 14 '17 at 15:17
Did you turn on "Acess for less secure apps" in your gmail settings ? — ISHIDA, Aug 14 '17 at 15:21
I did turn on Access for less secured apps, i put that in the question, i have also tried setting enableSsl to false. i have found the solution now though and have edited the question — chrisstar123, Aug 14 '17 at 15:23

score 11 · Accepted Answer · edited Aug 14 '17 at 15:41

11

Check your gmail account and turn on "Acess for less secure apps"
Set client.UseDefaultCredentials = false; before client.Credentials = new NetworkCredential("Sender email", "Sender email password");

edited Aug 14 '17 at 15:41

chrisstar123

77
1
2
8

answered Aug 14 '17 at 15:24

ISHIDA

4,700
2
16
30

the SMTP server requires a secure connection or the client was not authenticated. The server response was 5.5.1, Authentication required

1 Answers1