读取eml格式文件，并解析

直接用IdPop3处理比较好。注意主题要自己解码，不然会是乱码。
这里推荐我兄弟invalid的写的解码函数。
http://expert.youkuaiyun.com/Expert/FAQ/FAQ_Index.asp?id=35151
IdPop3的大致用法如下。

IdPOP31->Connect(30000);
Msg->Clear();
IdPOP31->Retrieve(k,Msg);

Msg->SaveToFile(IntToStr(k)+".msg",false);

 for(int i=0;i<Msg->Headers->Count;i++)
           
            Memo1->Lines->Add(UnCode(Msg->Headers->Strings[i]));

  if(Msg->ContentType.Pos("multipart/")>0){
            for(int i=0;i<Msg->MessageParts->Count;i++){
                if (dynamic_cast<TIdAttachment*>(Msg->MessageParts->Items[i])){ //附件
                    AnsiString fname=UnCode(dynamic_cast<TIdAttachment*>(Msg->MessageParts->Items[i])->FileName);
                    Memo1->Lines->Add(fname);
                    if(FileExists(fname))
                        DeleteFile(fname);
                    dynamic_cast<TIdAttachment*>(Msg->MessageParts->Items[i])->SaveToFile(fname);
                }
                else{
                    if(dynamic_cast<TIdText*>(Msg->MessageParts->Items[i]))
                        Memo1->Lines->AddStrings(dynamic_cast<TIdText*>(Msg->MessageParts->Items[i])->Body);
                }
            }
        }
        else{
            Memo1->Lines->AddStrings(Msg->Body);
        }