1. using System.Net.Mail;//引入这个命名空间
  3. 1.同步发送，程序将被阻塞
  4.  1  protected void Button1_Click(object sender, EventArgs e)
     2         {         
     3             string path = Server.MapPath("~/uploadfiles/" + FileUpload1.FileName);//FileUpload1控件
     4             FileUpload1.SaveAs(path);//保存上传的文件
     5             MailMessage mail = new MailMessage();
     6             mail.From = new MailAddress("xxx@qq.com", "发件人");//发件人地址，第二个参数表示发件人，可不要，
     7             mail.To.Add(new MailAddress("xxxx@126.com"));//收件人地址
     8             mail.Priority = MailPriority.High;  //优先级
     9             mail.Subject = "主题-发送时间：" + DateTime.Now;//主题
    10             mail.Body = "<a href='http://www.qq.com'>邮件内容</a>";//发送的正文
    11             mail.IsBodyHtml = true;//是否支持html的
    12             Attachment MsgAttach = new Attachment(path);//获取刚刚上传的文件的地址，
    13             mail.Attachments.Add(MsgAttach);//添加到附件
    14             SmtpClient server = new SmtpClient();//邮箱服务器对象
    15             server.Host = "smtp.qq.com";//服务器主机
    16             server.Credentials = new System.Net.NetworkCredential("pwd", "xxxxxx");//个人账号和密码
    17             server.Send(mail);
    18 
    19             //异步发送, 会进入回调函数SendCompletedCallback，来判断发送是否成功
    20 
    21         }


  5. 2.异步发送            // 异步发送必须在：<%@ Page%>添加Async="true"
  6.  1  protected void Button2_Click(object sender, EventArgs e)
     2         {
     3             try
     4             {
     5                 MailMessage mail = new MailMessage();
     6                 mail.From = new MailAddress("xxx@qq.com", "发件人");
     7                 mail.To.Add(new MailAddress("xxx@126.com"));
     8                 mail.Subject = "主题-发送时间:" + DateTime.Now;
     9                 mail.Body = "<a href='http://www.qq.com'>邮件内容</a>";
    10                 mail.IsBodyHtml = true;
    11                 
    12                 SmtpClient server = new SmtpClient();
    13                 server.Host = "smtp.qq.com";
    14                 server.Credentials = new System.Net.NetworkCredential("pwd", "xxxxxx");
    15                 server.SendCompleted += new SendCompletedEventHandler(SendCompletedCallback);//回调函数
    16                 string userState = "测试";
    17                 server.EnableSsl = true;
    18                 server.SendAsync(mail, userState);       
    19         ClientScript.RegisterClientScriptBlock(this.GetType(), "success", "<script>alert('发送成功')</script>");
    20             }
    21             catch(SmtpException ex)
    22             {
    23                 ClientScript.RegisterClientScriptBlock(this.GetType(), "fail", "<script>alert('发送失败，原因是："+ex.Message+"')</script>");
    24             }
    25         private static void SendCompletedCallback(object sender, System.ComponentModel.AsyncCompletedEventArgs e)
    26         {
    27 
    28             if (e.Cancelled)  //邮件发送被取消
    29             {
    30             }
    31 
    32             if (e.Error != null)   //邮件发送失败
    33             {
    34             }
    35 
    36             else   //发送成功
    37             {
    38             }
    39 
    40         }
  8. 当然有外国公司已经做好了现成的dll组件专门用于发送邮件，功能很强大，.net里面主要用到这2个dll
  9. Dimac.JMail.dll
  10. Dimac.JMail.Smtp.dll
  11. 网上有很多这关于JMail的文章
  12. 这2个dll和相关说明的下载地址：http://download.csdn.net/download/ccsnetmm/1903959。