private void sengmill_net()
  {//.net smtp类进行邮件发送，支持认证，附件添加；
   System.Web.Mail.MailMessage mailmsg = new System.Web.Mail.MailMessage();
   mailmsg.From = this.tb_from.Text.Trim();
   mailmsg.To   = this.tb_to.Text.Trim();
   mailmsg.Body = this.tb_mailBody.Text.Trim();
   mailmsg.Subject = "test mail from hz";
   /* 附件的粘贴, ^_^,笨了点;
   if(this.att1.Value.ToString().Trim()!=string.Empty)
    mailmsg.Attachments.Add(new System.Web.Mail.MailAttachment(this.att1.Value.ToString().Trim()));
   if(this.att2.Value.ToString().Trim()!=string.Empty)
    mailmsg.Attachments.Add(new System.Web.Mail.MailAttachment(this.att2.Value.ToString().Trim()));
   if(this.att3.Value.ToString().Trim()!=string.Empty)
    mailmsg.Attachments.Add(new System.Web.Mail.MailAttachment(this.att3.Value.ToString().Trim()));
   */
   mailmsg.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate", "1");
   //是否需要验证，一般是要的    
   mailmsg.Fields.Add
    ("http://schemas.microsoft.com/cdo/configuration/sendusername", "gallon_han");
   //自己邮箱的用户名    
   mailmsg.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendpassword", "218500");
   //自己邮箱的密码 
   System.Web.Mail.SmtpMail.SmtpServer = this.tb_smtpserver.Text.Trim();
   System.Web.Mail.SmtpMail.Send(mailmsg);
  }