简单的实现用户注册时，向其油箱发送激活码邮件，并进行状态处理。 .

注册页面：

后台：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Configuration;
using System.Data.SqlClient;
using System.Net.Mail;
using System.Text;
using System.Net;

namespace 激活验证
{
    public partial class region : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }

         public void sendMail(string Email,string activeCode)
        {
            MailMessage msg = new MailMessage();
            msg.From=new MailAddress("duan_linlin@163.com");  //邮件来自哪
            msg.To.Add(Email);
             msg.Subject = "请激活注册！";

             StringBuilder contentBuilder=new StringBuilder();
             contentBuilder.Append("请单击一下连接完成激活！");
             contentBuilder.Append("<a href='http://localhost:1950/CheckActiveCode.aspx?activecode="+activeCode+"&id=3'>激活</a>");

             msg.Body = contentBuilder.ToString();

             msg.IsBodyHtml=true;
             SmtpClient client = new SmtpClient(); //允许传输协议
             client.Host = "smtp.163.com";   //发件方服务器地址
             client.Port = 25;  //发件方端口
             NetworkCredential credential = new NetworkCredential();
             credential.UserName = "duan_linlin@163.com";
             credential.Password = "jinyuxueqi521";
             client.Credentials = credential;  //说明证书要给代理证书credential
             client.Send(msg);
        }

        protected void Button1_Click(object sender, EventArgs e)
        {
            string userName = TextBox1.Text.Trim();
            string password = TextBox2.Text.Trim();
            string Email = TextBox3.Text.Trim();

            string activeCode = Guid.NewGuid().ToString().Substring(0, 8);  //生成激活码

            string conStr = ConfigurationManager.ConnectionStrings["conStr"].ConnectionString;
          
            int number;
            using (SqlConnection con=new SqlConnection(conStr))
            {
                string sql = "insert into T_Users (UserName,Password,Email,Active,ActiveCode) values(@username,@password,@Email,@active,@activecode)";
                SqlParameter[] prams = new SqlParameter[]{
                new SqlParameter("@username",userName),
                new SqlParameter("@password",password),
                new SqlParameter("@Email",Email),
                new SqlParameter("@active",false),
                new SqlParameter("@activecode",activeCode)
                };

                using (SqlCommand cmd=new SqlCommand(sql,con))
                {
                    con.Open();
                    cmd.Parameters.AddRange(prams);

                   number= cmd.ExecuteNonQuery();
                }
            }

            if (number>0)
         {   
          sendMail( Email, activeCode);//给注册用户发邮件

                Response.Redirect("regionMessage.aspx");
         }
            else
             {
               Response.Write("注册失败");
               }
           
        }

      

    }
}

CheckActiveCode后台：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using System.Configuration;

namespace 激活验证
{
    public partial class CheckActiveCode : System.Web.UI.Page
    {    
        string conStr = ConfigurationManager.ConnectionStrings["conStr"].ConnectionString;
        int  number;
        protected void Page_Load(object sender, EventArgs e)
        {
            //去除参数id
            int id = Convert.ToInt32(Request["id"]);

            string activeCode = Request["ActiveCode"].ToString();

            //判断id为id的记录值是否存在
            //连接数据库
       
            using (SqlConnection con = new SqlConnection(conStr))
            {
                string sql = "select count(*) from T_Users where id=@id";
                using (SqlCommand cmd=new SqlCommand(sql,con))
                {
                    con.Open();
                    cmd.Parameters.AddWithValue("@id", id);

                    number = Convert.ToInt32(cmd.ExecuteScalar());

                }
            }

            if ( number > 0)
            {
                //如果该用户存在取出其ActiveCode字段进行比较，如果一样，把Active字段修改为true。
                //连接数据库
                string AC;
                using (SqlConnection con = new SqlConnection(conStr))
                {
                    string sql = "select ActiveCode from T_Users where id=@id";
                    using (SqlCommand cmd = new SqlCommand(sql, con))
                    {
                        con.Open();
                        cmd.Parameters.AddWithValue("@id", id);

                        AC =cmd.ExecuteScalar().ToString();

                    }
                }

                if (activeCode == AC)
                {
                    Response.Write("激活成功！");

                    //连接数据库
                    using (SqlConnection con = new SqlConnection(conStr))
                    {
                        string sql = "update T_Users set Active=1 where id=@id";
                        using (SqlCommand cmd = new SqlCommand(sql, con))
                        {
                            con.Open();
                            cmd.Parameters.AddWithValue("@id", id);

                            number =Convert.ToInt32(cmd.ExecuteScalar());

                        }
                    }
                }

                else
                {
                    Response.Write("用户存在，但是激活码错误！");
                }

            }
            else
            {
                Response.Write("用户不存在！注册失败！");           
            }
        }
    }
}

regionMessage前台：

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="regionMessage.aspx.cs" Inherits="激活验证.regionMessage" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
   <h2> 恭喜你注册成功！</h2>
    </div>
    </form>
</body>
</html>