电子邮件 问题
protected void btnSend_Click(object sender, EventArgs e)
  {
  if (this.txtReceiver.Text != string.Empty && this.txtSender.Text != string.Empty)
  {
  //创建邮件
  MailMessage myMail = new MailMessage(this.txtSender.Text.Trim(), this.txtReceiver.Text.Trim(), this.txtSubject.Text.Trim(), this.txtContent.Text.Trim());
  myMail.Priority = System.Net.Mail.MailPriority.High;这里有什么作用?
  //创建附件对象
  string sFilePath = this.upFile.PostedFile.FileName;这里是不是指选择附件的名字?;
  FileInfo fi = new FileInfo(sFilePath);
if(fi.Exists) 这两名什么意思? {
  System.Net.Mail.Attachment myAttachment = new System.Net.Mail.Attachment(sFilePath, System.Net.Mime.MediaTypeNames.Application.Octet);这个是不是指附件的类型?  
System.Net.Mime.ContentDisposition disposition = myAttachment.ContentDisposition;这名什么意思?
  disposition.CreationDate = System.IO.File.GetCreationTime(sFilePath);
  disposition.ModificationDate = System.IO.File.GetLastWriteTime(sFilePath);
  disposition.ReadDate = System.IO.File.GetLastAccessTime(sFilePath);
  myMail.Attachments.Add(myAttachment);
   
  }
  //发送邮件
  System.Net.Mail.SmtpClient client = new System.Net.Mail.SmtpClient("smtp.126.com ", 25);
  client.Credentials = new System.Net.NetworkCredential(this.txtSUser.Text.Trim(),this.txtEPwd.Text.Trim());
  client.Send(myMail);
 

------解决方案--------------------
myMail.Priority = System.Net.Mail.MailPriority.High;//设置邮件优先级，发出后邮件会显示感叹号加急或下箭头缓慢等标识
//创建附件对象
string sFilePath = this.upFile.PostedFile.FileName;//获取上传控件文件名;
FileInfo fi = new FileInfo(sFilePath);
if(fi.Exists) //判断文件是否存在 {
System.Net.Mail.Attachment myAttachment = new System.Net.Mail.Attachment(sFilePath, System.Net.Mime.MediaTypeNames.Application.Octet);//指定文件类型，不确定可选此项
System.Net.Mime.ContentDisposition disposition = myAttachment.ContentDisposition;//设置文件属性,MIME类型