Vfrdtyky

I am trying to send an email using default credentials and the SMTPClient.

The exception I get is:

The SMTP Server requires a secured connection, or the client was not authenticated. The serverresponse was: 5.7.1 Client was not authenticated.

The code I am trying to use:

public void SendEmail(List<string> recipients, string subject, string body)

{

    if (recipients.Count == 0)

        return;



    MailMessage mail = new MailMessage();

    SmtpClient client = new SmtpClient();

    foreach (string to in recipients)

    {

        mail.To.Add(to);                

    }



    mail.From = new MailAddress("email@email.com");

    client.Port = 25;

    client.DeliveryMethod = SmtpDeliveryMethod.Network;

    client.UseDefaultCredentials = true;

    client.Host = "smtprelay.email.com";



    //client.Credentials = new System.Net.NetworkCredential("email@email.com", password);

    ServicePointManager.ServerCertificateValidationCallback = delegate (object s, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors) { return true; };



    client.EnableSsl = true;

    mail.Subject = subject;

    mail.Body = body;

    mail.IsBodyHtml = true;



    try

    {

        client.Send(mail);

    }

    catch(Exception e)

    {

        Console.Write(e.Message);

    }

    mail.Dispose();

}

I tested with EnableSsl = true and false, neither worked. If I set UseDefaultCredentials to false, and give them via NetworkCredential, then it works.

Is there some setting in exchange or such that needs to be set?

Edit: int the ServerCertificateCallback, I get:
'((System.Net.Mail.SmtpClient)s).ServicePoint.Address' threw an exception of type 'System.NotSupportedException'

and sslPolicyErrors was System.Net.Security.SslPolicyErrors.RemoteCertificateNameMismatch

Does that mean the group policies do not allow this?

Exchange requires either a valid domain account (login/pw) or an IP address that your postmaster has configured as allowable.

you can try this code below

public static void logMail(string err)

        {

            SmtpClient smtp = new SmtpClient();

            smtp.Credentials = new System.Net.NetworkCredential("email@email.com", "password");

            smtp.Port = 25;

            smtp.Host = "mail.email.com";



            MailAddress from = new MailAddress("email@email.com", "test");

            MailAddress to = new MailAddress("vb_error@email.com"); 

            MailMessage mail = new MailMessage(from, to);

            mail.IsBodyHtml = true;

            mail.Subject = "Error";

            mail.Body = "<b>Error Message:</b> " + err;

            smtp.Send(mail);

        }