以Windows窗体发送邮件

在windows窗体中，我编写了一个发送邮件的代码，我将邮件设置放在app.config中，你能检查一下我的代码吗。它正确与否。

<configuration>
  <system.net>
<mailSettings>
  <smtp from="someaddress@mydomain.com">
    <network host="mail.mydomain.com" password="xxxxxx" port="25" userName="someaddress@mydomain.com"/>
  </smtp>
</mailSettings>

        MailMessage msg = new MailMessage();
        msg.Subject = txtSubject.Text;
        msg.To.Add(txtTO.Text);
        msg.From = new MailAddress("suryasasidhar13@gmail.com");
        msg.Body = txtDescription.Text;
        System.Net.Configuration.MailSettingsSectionGroup mMailSettings=null ;
        string mMailHost = mMailSettings.Smtp.Network.Host;
        SmtpClient mailClient = new SmtpClient(mMailHost);
        mailClient.Send(msg);