服务器响应为：5.7.0在System.Net.Mail.SmtpTransport的时间范围太短的消息太多

Question

我正在开发一个发送批量邮件的Windows应用程序 它成功地用于100封邮件。之后它开始显示 这些错误

  

服务器响应为：5.7.0在时间框架太短的情况下，消息过多   System.Net.Mail.SmtpTransport.SendMail（
  邮件地址发件人，
  MailAddressCollection收件人，
  字符串传递通知，
  布尔值allowUnicode，
  SmtpFailedRecipientException＆安培;除外）
     在System.Net.Mail.SmtpClient.Send（MailMessage消息）
     在SmsAndEmail.Email.EmailIndex.SendTheMail（）

这是我的代码：

MailMessage msg = new MailMessage();
msg.From = new MailAddress("MailAddress");
msg.To.Add(mail.ToAddress);
msg.Subject = "MySub";
msg.Body = mail.EmailBody;
SmtpClient client = new SmtpClient();
client.UseDefaultCredentials = true;
client.Host = "hostname";
client.Port = 587;
client.EnableSsl = false;
client.DeliveryMethod = SmtpDeliveryMethod.Network;
client.Credentials = new NetworkCredential("MailAddress", "password");
client.Timeout = 20000;
ServicePointManager.ServerCertificateValidationCallback =
  delegate(
    object s, 
    X509Certificate certificate,
    X509Chain chain, 
    SslPolicyErrors sslPolicyErrors
  )
  { return true; }
;
try
{
    client.Send(msg);
    newStatus = "SUCCESS";
}
catch (Exception ex)
{
    newStatus = "Failed";
    errorMessage = "Mail Sending Failed !";
    return errorMessage;
}