The message was undeliverable. All servers failed to receive the message

The message was undeliverable. All servers failed to receive the message,使用Jmail自己给自己发没问题，自己别发就有问题了!
 string sendName = txtMailName.Text;
            string receiveAddress = txtReveiveAddress.Text;
            string sendAddress = txtSendAddress.Text;
            string content = txtContent.Text;
            string subject=txtSubject.Text;            Message message = new Message();
            message.Logging = true;
            message.Charset = "gb2312";
            message.MailServerUserName = receiveAddress;
            message.MailServerPassWord = txtPassword.Text;
                     //邮件的发送者
            message.From = sendAddress;
            message.FromName = sendName;            //邮件的接收者
            message.AddRecipient(receiveAddress, "", "A");            //邮件的主题
            message.Subject = subject;            //邮件的正文
            message.Body = content;            //邮件发送
            if (message.Send("smtp.163.com", false))
            {
                Response.Write("发送成功！<br>");
            }
            else
            {
                Response.Write("失败!<br>");
            }