jmail接收邮件：

private void BtnTake_Click(object sender, System.EventArgs e)
  {
   jmail.POP3Class popMail = new POP3Class();//建立收邮件对象
   jmail.Message mailMessage;  //建立邮件信息接口
   jmail.Attachments atts;//建立附件集接口
   jmail.Attachment att;//建立附件接口

   try
   {
    popMail.Connect(TxtPopUser.Text.Trim(),TxtPopPwd.Text.Trim(),TxtPopServer.Text.Trim(),Convert.ToInt32(TxtPopPort.Text.Trim()));

    if(0 < popMail.Count)                                                                          //如果收到邮件
    {
     for(int i=1;i <= popMail.Count;i++)                                                         //根据取到的邮件数量依次取得每封邮件
     {
      mailMessage = popMail.Messages[i];                                                        //取得一条邮件信息
      atts = mailMessage.Attachments;                                                           //取得该邮件的附件集合
      mailMessage.Charset = "GB2312";                                                           //设置邮件的编码方式
      mailMessage.Encoding = "Base64";                                                          //设置邮件的附件编码方式
      mailMessage.ISOEncodeHeaders = false;                                                     //是否将信头编码成iso-8859-1字符集
      txtpriority.Text = mailMessage.Priority.ToString();                                       //邮件的优先级                
      txtSendMail.Text = mailMessage.From;                                                      //邮件的发送人的信箱地址
      txtSender.Text = mailMessage.FromName;                                                    //邮件的发送人
      txtSubject.Text = mailMessage.Subject;                                                    //邮件主题
      txtBody.Text = mailMessage.Body;                                                          //邮件内容
      txtSize.Text = mailMessage.Size.ToString();                                                          //邮件大小
      
      for(int j=0;j<atts.Count;j++)
      {
       att = atts[j];                                                                        //取得附件
       string attname = att.Name;                                                            //附件名称
       
       att.SaveToFile("e:\\attFile\\"+attname);                                              //上传到服务器
       
      }
      
     }
     panMailInfo.Visible = true;
     att = null;
     atts = null;
    }
    else
    {
     Response.Write("没有新邮件!");
    }

    popMail.DeleteMessages();
    popMail.Disconnect();
    popMail = null;
   }
   catch
   {
    Response.Write("Warning!请检查邮件服务器的设置是否正确！");
   }
  }

jmail发邮件
private void btnSend_Click(object sender, System.EventArgs e)
  {
   jmail.MessageClass oJmailMessage = new jmail.MessageClass();//建立发邮件类

   oJmailMessage.Charset = "GB2312";// 字符集
   oJmailMessage.Encoding = "BASE64";//附件的编码格式
   oJmailMessage.ContentType = "text/html";
   oJmailMessage.ISOEncodeHeaders = false;//是否将信头编码成iso-8859-1字符集
   oJmailMessage.Priority = Convert.ToByte(1);// 优先级
  
   oJmailMessage.From = TxtEmail.Text.Trim();//发送人邮件地址
   oJmailMessage.FromName = TxtName.Text.Trim();//发送人姓名
   oJmailMessage.Subject = txtSubject.Text.Trim();// 邮件主题
   oJmailMessage.MailServerUserName = TxtSmtpUser.Text.Trim();//身份验证的用户名
   oJmailMessage.MailServerPassWord = TxtSmtpPwd.Text.Trim();//用户密码

   //添加一个收件人，抄送人和密送人的添加和该方法是一样的，只是分别使用AddRecipientCC和RecipientBCC两个属性
   //要是需要添加多个收件人，则重复下面的语句即可。添加多个抄送和密送人的方法一样
   oJmailMessage.AddRecipient(txtReciver.Text.Trim(),"","");
   if("" != upFile.PostedFile.FileName)
   {
    string attpath = upFile.PostedFile.FileName;
    oJmailMessage.AddAttachment(@attpath,true,attpath.Substring(attpath.LastIndexOf(".")+1,3));//添加附件
   }
   oJmailMessage.Body = txtContent.Text.Trim();//邮件内容

   if(oJmailMessage.Send(TxtSmtServer.Text.Trim(),false))
   {
    Response.Write("发送成功！");
   }
   else
   {
    Response.Write("发送失败，请检查邮件服务器的设置！");
   }

   oJmailMessage = null;
  }

运行该示例需要注意的地方：
1.jmail.dll组件需要在运行该程序的机器上进行注册，可通过如下方式注册：
 进入Dos模式，输入"regsvr32 jmail.dll组件所在路径"，然后回车，即可在机器上完成jmail.dll组件的注册。
2.如果您的机器上装有瑞星等杀毒软件，请关闭其“邮件发送监控，及邮件接受监控”功能。
3.正确设置邮件服务器。