通过内建SMTP服务器发送邮件失败

jackzhang520

系统发送邮件使用SMTP IP地址发送时，发送失败！
备注：SMTP不用帐号密码验证，但不允许匿名发送

以下C#代码使用SMTP服务器发送正常
private string Send(string Body, string Mailto, string CCMailto, string Title)
      {
         try
         {
            System.Net.Mail.MailMessage message = new System.Net.Mail.MailMessage(sSmtpMailFrom, Mailto, Title, Body + SendPS);
            message.SubjectEncoding = System.Text.Encoding.UTF8;/
            message.BodyEncoding = System.Text.Encoding.UTF8;
            message.IsBodyHtml = true;
            message.Priority = MailPriority.High;
            if (CCMailto.Length > 0)
            {
                  message.CC.Add(CCMailto);
            }
            System.Net.Mail.SmtpClient client = new System.Net.Mail.SmtpClient(sSmtpIP, sSmtpPort);
            client.UseDefaultCredentials = false;
            client.DeliveryMethod = SmtpDeliveryMethod.Network;
            client.Send(message);
            return "Success";
         }
         catch (Exception exp)
         {
            return exp.Message;
         }
}