C# SMTP authentication failed but credentials are correct

Question

Here is my problem: I wrote whe following program to test if I can send email:

class Program
{
    static void Main(string[] args)
    {
        try {
                   


        

Answer 1

While I had encountered the same issue, I found a solution to the issue here

In short, you must use

smtp.UseDefaultCredentials = false;

AFTER

smtp.Credentials = new NetworkCredential(ConfigurationManager.AppSettings["email.username"].ToString(), 
                                         ConfigurationManager.AppSettings["email.password"].ToString());

So quick summary, something that would look more like this should work:

        SmtpClient smtp = new SmtpClient();
        smtp.Host = ConfigurationManager.AppSettings["email.smtp"].ToString();
        smtp.Port = Convert.ToInt32(ConfigurationManager.AppSettings["email.port"]);
        smtp.Credentials = new NetworkCredential(ConfigurationManager.AppSettings["email.username"].ToString(), 
                                                 ConfigurationManager.AppSettings["email.password"].ToString());
        smtp.UseDefaultCredentials = false;
        smtp.EnableSsl = Convert.ToBoolean(ConfigurationManager.AppSettings["email.enablessl"]);
        Console.WriteLine("Sending email..." + (i+1));
        smtp.Send(mail);