邮件附件格式

if(附件绝对路径!="")//添加附件
{
    System.Net.Mime.ContentType type = new System.Net.Mime.ContentType("application/vnd.openxmlformats-officedocument.wordprocessingml.document");
    System.Net.Mail.Attachment objAtt = new System.Net.Mail.Attachment(附件绝对路径, type); 
    ObjMail.Attachments.Add(objAtt); 
    ContentDisposition disposition = objAtt.ContentDisposition; disposition.DispositionType = "attachment;\t filename=" + Path.GetFileName(附件绝对路径); 
}

 邮件原文格式
-----------=_VxiQcghCADTbNqgPmLRpqAGvcowuwOnorRmShm
Content-Type: application/octet-stream; 内容是应用，即附件
  name="aa.doc"  附件应用名
Content-Transfer-Encoding: base64 编码格式
Content-Disposition: attachment; 内容描述：附件 
  filename="aa.doc"