使用smtp发送邮件时无法发送邮件异常

Question

这是我的发送电子邮件代码 当我执行此代码时，有时会成功发送邮件，但大多数情况下会抛出“发送邮件失败” 的期望。我还检查了网络凭据是否正确

为什么会出现此错误？

 mail.Subject = emailSubject;
 mail.Body = emailBody;
 mail.IsBodyHtml = true;
 SmtpClient smtp = new SmtpClient();
 smtp.Host = emailServerHost;
 smtp.Port = intEmailServerPort;
 smtp.Credentials = new System.Net.NetworkCredential(emailServerLoginName, 
 fromEmailPassword);
 smtp.EnableSsl = true;
 ServicePointManager.ServerCertificateValidationCallback = delegate(object s, 
 X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors) 
 {return true;}; 
 smtp.Send(mail);
 return true;
 }
 else
  return false;
 }
        catch (Exception ex)
        {
            ErrorLoger(ex, "SendEmail", clientContext);
            return false;


        }
    }