Email Error System.Net.Mail.SmtpException

Hi

  I am getting error - System.Net.Mail.SmtpException
  HResult=0x80131500
  Message=The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.0 Authentication Required. For more information, go to
  Source=System.Net.Mail
  StackTrace:
   at System.Net.Mail.MailCommand.CheckResponse(SmtpStatusCode statusCode, String response)
   at System.Net.Mail.SmtpTransport.SendMail(MailAddress sender, MailAddressCollection recipients, String deliveryNotify, Boolean allowUnicode, SmtpFailedRecipientException& exception)
   at System.Net.Mail.SmtpClient.Send(MailMessage message)
   at Atulaya.Form1..ctor() in C:\Users\Administrator\source\repos\Atulaya\Atulaya\Form1.cs:line 97
   at Atulaya.Program.Main() in C:\Users\Administrator\source\repos\Atulaya\Atulaya\Program.cs:line 14

I have below code

            var addresses = "[email protected];[email protected]";
            var fromAddress = new MailAddress("[email protected]", "Sender");
            const string fromPassword = "Password";
            string subject = "[Message] Message Subject";
            string body = "Hi, Test Email";

            var smtp = new SmtpClient
            {
                Host = "smtp.gmail.com",
                Port = 587, 
                EnableSsl = true,
                DeliveryMethod = SmtpDeliveryMethod.Network,
                UseDefaultCredentials = false,
                Credentials = new NetworkCredential(fromAddress.Address, fromPassword)
            };
            foreach (var address in addresses.Split(new[] { ";" }, StringSplitOptions.RemoveEmptyEntries))
            {
                using (var message = new MailMessage(fromAddress.ToString(), address)
                {
                    Subject = subject,
                    Body = body,
                    Priority = MailPriority.High

                })
                {

                    smtp.Send(message);
                }
            }