如何在.NET 中简单使用SMTP发送邮件？

public class Mail
    {
        #region 邮件参数
        static public string accountName = System.Configuration.ConfigurationManager.AppSettings["SmtpAccountName"];
        static public string password = System.Configuration.ConfigurationManager.AppSettings["SmtpAccountPW"];
        static public string smtpServer = System.Configuration.ConfigurationManager.AppSettings["SmtpServer"];
        static public int smtpPort = int.Parse(System.Configuration.ConfigurationManager.AppSettings["SmtpPort"]);
        #endregion

        /// <summary>
        /// 邮件发送方法一
        /// </summary>
        /// <param name="sendTo"></param>
        /// <param name="subject"></param>
        /// <param name="body"></param>
        static public void SendMail(string sendTo, string subject, string body)
        {
            //.net smtp 
            System.Web.Mail.MailMessage mailmsg = new System.Web.Mail.MailMessage();
            mailmsg.To = sendTo;
            //mailmsg.Cc = cc;
            mailmsg.Subject = subject;
            mailmsg.Body = body;
            mailmsg.BodyFormat = MailFormat.Html;


            //sender here
            mailmsg.From = Mail.accountName;
            // certify needed 
            mailmsg.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate", "1");//1 is to certify
            //the user id 
            mailmsg.Fields.Add(
            "http://schemas.microsoft.com/cdo/configuration/sendusername",
            Mail.accountName);
            //the password
            mailmsg.Fields.Add(
            "http://schemas.microsoft.com/cdo/configuration/sendpassword",
            Mail.password);

            System.Web.Mail.SmtpMail.SmtpServer = Mail.smtpServer;

            System.Web.Mail.SmtpMail.Send(mailmsg);

        }
        /// <summary>
        /// 邮件发送方法二
        /// </summary>
        /// <param name="sendTo"></param>
        /// <param name="subject"></param>
        /// <param name="body"></param>
        static public void SendMail2(string sendTo, string subject, string body)
        {
            System.Net.Mail.MailMessage msg = new System.Net.Mail.MailMessage(accountName, sendTo, subject, body);
            msg.From = new System.Net.Mail.MailAddress(accountName, "Mail");
            System.Net.Mail.SmtpClient client = new System.Net.Mail.SmtpClient(smtpServer);
            msg.IsBodyHtml = true;
            client.Credentials = new System.Net.NetworkCredential(accountName, password);
            client.DeliveryMethod = System.Net.Mail.SmtpDeliveryMethod.Network;

            client.Send(msg);
        }
    }