无法将消息发送到电子邮件

//send email
MailMessage objEmail = new MailMessage(new MailAddress(ConfigurationManager.AppSettings[\"emailAdd\"].ToString()), new MailAddress(ConfigurationManager.AppSettings[\"emailAdd\"].ToString()));
objEmail.Subject = \"Test\";
objEmail.Body = _Message;
objEmail.Priority = MailPriority.High;
SmtpClient SmtpMail = new SmtpClient();
SmtpMail.Host = \"localhost\";
SmtpMail.Send(objEmail);