.NET实现定时发送邮件代码（两种方式）

void Application_Start(object sender, EventArgs e)  {   // 在应用程序启动时运行的代码   System.Timers.Timer timer = new System.Timers.Timer();//设计时间间隔，如果一个小时执行一次就改为   timer.Elapsed += new System.Timers.ElapsedEventHandler(Send);   timer.AutoReset = true;   timer.Enabled = true;  }   void Application_End(object sender, EventArgs e)  {   // 在应用程序关闭时运行的代码   System.Threading.Thread.Sleep();   string strUrl = "服务器地址";   System.Net.HttpWebRequest _HttpWebRequest = (System.Net.HttpWebRequest)System.Net.WebRequest.Create(strUrl);   System.Net.HttpWebResponse _HttpWebResponse = (System.Net.HttpWebResponse)_HttpWebRequest.GetResponse();   System.IO.Stream _Stream = _HttpWebResponse.GetResponseStream();//得到回写的字节流   _HttpWebResponse.Close();  }   void Application_Error(object sender, EventArgs e)  {   // 在出现未处理的错误时运行的代码   }   void Session_Start(object sender, EventArgs e)  {   // 在新会话启动时运行的代码   }   void Session_End(object sender, EventArgs e)  {   // 在会话结束时运行的代码。    // 注意: 只有在 Web.config 文件中的 sessionstate 模式设置为   // InProc 时，才会引发 Session_End 事件。如果会话模式设置为 StateServer   // 或 SQLServer，则不引发该事件。   }   private void Send(object sender, System.Timers.ElapsedEventArgs e)  {   switch (DateTime.Now.Hour)   {    case :    case :     SendEMail();     break;    //default:    // SendEMail();    // break;   }  }  private void SendEMail()  {   string mailFrom = System.Configuration.ConfigurationManager.AppSettings["MailFrom"].ToString();   string mailUser = System.Configuration.ConfigurationManager.AppSettings["MailUser"].ToString();   string mailPassword = System.Configuration.ConfigurationManager.AppSettings["MailPassword"].ToString();   string hostIP = System.Configuration.ConfigurationManager.AppSettings["MailHost"].ToString();    List<string> mailAddress = new List<string>();   string mailSubjct = "邮件主题";    string mailBody = "邮件内容:"；   mailAddress.Add("邮件地址");string strReturn = sendMail(mailSubjct, mailBody, mailFrom, mailAddress, hostIP, mailUser, mailPassword, false);  }

 public static string sendMail(string mailSubjct, string mailBody, string mailFrom, List<string> mailAddress, string hostIP, string username, string password, bool ssl)   {    string str = "";    try    {     MailMessage message = new MailMessage     {      IsBodyHtml = true,      Subject = mailSubjct,      Body = mailBody,       From = new MailAddress(mailFrom)     };     for (int i = ; i < mailAddress.Count; i++)     {      message.To.Add(mailAddress[i]);     }     SmtpClient client = new SmtpClient     {      EnableSsl = ssl,      UseDefaultCredentials = false     };     NetworkCredential credential = new NetworkCredential(username, password);     client.Credentials = credential;     client.DeliveryMethod = SmtpDeliveryMethod.Network;     client.Host = hostIP;     client.Port = x;     client.Send(message);    }    catch (Exception exception)    {     str = exception.Message;    }    return str;   }

using System.Net.Mail; using System.Timers; protected void Application_Start(object sender, EventArgs e)   {    Timer t = new Timer(60000);//设计时间间隔，如果一个小时执行一次就改为3600000 ，这里一分钟调用一次    t.Elapsed += new ElapsedEventHandler(t_Elapsed);    t.AutoReset = true;    t.Enabled = true;   }   private void t_Elapsed(object sender, ElapsedEventArgs e)   {    MailMessage message = new MailMessage();    message.From = Messagefrom;    message.To.Add(MessageTo);    //收件人邮箱地址可以是多个以实现群发    message.Subject = MessageSubject;    message.Body = MessageBody;    message.IsBodyHtml = true;    //是否为html格式    message.Priority = MailPriority.High; //发送邮件的优先等级    SmtpClient sc = new SmtpClient();    sc.Host = "smtp.sina.com";    //指定发送邮件的服务器地址或IP    sc.Port = 25;       //指定发送邮件端口    //sc.UseDefaultCredentials = true;    //sc.EnableSsl = true;    sc.Credentials = new System.Net.NetworkCredential(“**@**”, "密码"); //指定登录服务器的用户名和密码     sc.Send(message);  //发送邮件   }