ASP.NET发送电子邮件

谢谢

web.config中的代码：

<system.net>
<mailSettings>
  <smtp from="order@test.com">
    <network host="smtp.gmail.com"
             userName="" //my email
             password="" //password deleted for privacy reasons
             defaultCredentials="false"
             port="456"
             enableSsl="true" />
  </smtp>
</mailSettings>

asp.net联系表格中的代码：

protected void btnSubmit_Click(object sender,EventArgs e)
    {
        MailMessage mail = new MailMessage();
        mail.To.Add(new MailAddress("test@gmail.com"));
        mail.Subject = "Test";
        mail.Body = "Message was sent from" + txtName.text + txtComment.text;
        SmtpClient smtp = new SmtpClient();
        smtp.SendAsync(mail,null);
    }