protected void Button1_Click(object sender, EventArgs e)
        {
            SendSMTPEMail("smtp.qq.com", "[email protected]", "XX密码XXXX", "[email protected]", "123", "用asp.net发送邮件，用qq的smtp.qq.com服务器，测试成功");
            
        }

        public void SendSMTPEMail(string strSmtpServer, string strFrom, string strFromPass, string strto, string strSubject, string strBody)
        {
            System.Net.Mail.SmtpClient client = new SmtpClient(strSmtpServer);
            client.UseDefaultCredentials = false;
            client.Credentials = new System.Net.NetworkCredential(strFrom, strFromPass);
            client.DeliveryMethod = SmtpDeliveryMethod.Network;
            System.Net.Mail.MailMessage message = new MailMessage(strFrom, strto, strSubject, strBody);
            message.BodyEncoding = System.Text.Encoding.UTF8;
            message.IsBodyHtml = true;
            client.Send(message);
        }
        //第一个参数是邮箱服务器
        //第二个参数发件人的帐号
        //第三个参数发件人密码
        //第四个参数收件人帐号
        //第五个参数主题
        //第六个参数内容.

 public void SendMailUseZj()
    {
        System.Net.Mail.MailMessage msg = new System.Net.Mail.MailMessage();

        //msg.To.Add("[email protected]");
        msg.To.Add(“这里填发给地址如[email protected]”);
        
        // msg.To.Add("[email protected]");
        //可以发送给多人 
       
        //msg.CC.Add("[email protected]");
        //可以抄送给多人 
        
        msg.From = new MailAddress("[email protected]", "SFADSXCVXXV", System.Text.Encoding.UTF8);/* 上面3个参数分别是发件人地址（可以随便写），发件人姓名，编码*/
        msg.Subject = "aaaaa" ;//邮件标题 
        msg.SubjectEncoding = System.Text.Encoding.UTF8;//邮件标题编码 
        msg.Body = "adsssssssss";//邮件内容 
        msg.BodyEncoding = System.Text.Encoding.UTF8;//邮件内容编码 
        msg.IsBodyHtml =true;//是否是HTML邮件 
        //msg.Priority = MailPriority.High;//邮件优先级 

        SmtpClient client = new SmtpClient();
        client.Credentials = new System.Net.NetworkCredential("[email protected]", "77777777"); //发送的邮箱账号密码。这肯定得写你自己的,我用的126
        client.Host = "smtp.126.com";
        object userState = msg;
        try
        {
            //client.SendAsync(msg, userState);
            client.Send(msg);
            Label1.Text = "发送成功！！";
        }
        catch (System.Net.Mail.SmtpException ex)
        {
           Label1.Text = "发送失败!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!";//前台的标签，不用说了吧
        }
    }

POP3：pop.163.com
SMTP：smtp.163.com

新浪免费邮箱发信(smtp)服务器的地址为：smtp.sina.com

新浪免费邮箱收信(pop3)服务器的地址为：pop.sina.com

其他的在网上找吧。。