Code
public class EmailConfig
{
   static private readonly string configpath= "~/config/email.config";
   static private bool _enablessl;
    /// <summary>
        /// 静态构造函数
        /// </summary>
        static EmailConfig()
        {
            Reload();
        }
        /// <summary>
        /// 重新读取Config文件，重新取值
        /// </summary>
        static public void Reload()
        {
            string filepath = HttpContext.Current.Server.MapPath(configpath);
            XmlDocument xml = new XmlDocument();
            xml.Load(filepath);
            XmlNode rootpor = xml.SelectSingleNode("email/setting");
            _mode = rootpor.Attributes["current"].Value;
            foreach (XmlNode n in rootpor.ChildNodes)
            {
                if (n.NodeType != XmlNodeType.Comment && n.Name.ToLower() == "parameter")
                {
                    _host = n.Attributes["host"].Value;
                    _port = int.Parse(n.Attributes["port"].Value);
                    _from = n.Attributes["from"].Value;
                    _username = n.Attributes["username"].Value;
                    _password = n.Attributes["password"].Value;
                    if (n.Attributes["enablessl"].Value.ToLower() == "true")
                        _enablessl = true;
                    else
                        _enablessl = false;
                }
            }
        }
}