关于文件中提取邮件老鸟门能不能给个思路或者算法，小弟谢谢了

void CEAPDlg::BrowseDir(CString strDir)
{
    CString flagstr(" \"<>\r\n[]{}:;=,'?#!`^$*%()");
    int bufsize = m_list.GetCount();
    CString *Word = new CString [bufsize];
    for(int i=0;i<bufsize;i++)
    {
        m_list.GetText(i,Word[i]);
    }
    
    CFileFind finder;
    CString szDir = strDir;
    
    if(szDir.Right(1) != "\\")
        szDir += "\\";

    szDir += "*.*";
    
    BOOL res = finder.FindFile(szDir);
    while( res )
    {
        res = finder.FindNextFile();
        if(finder.IsDirectory() && !finder.IsDots())
        {
            CString strPath = finder.GetFilePath();
            CString strFileName = finder.GetFileName();
            BrowseDir( strPath );
        }
        else if(!finder.IsDirectory() && !finder.IsDots())
        {
            CString strFileName = finder.GetFileName();
            CString strFilePathName = finder.GetFilePath();
            CString name = strFileName.Right(4);
            if((name.Find(".eml") != -1) ||
                (name.Find(".txt") != -1) ||
                (name.Find(".dbx") != -1) )
            {
                CFile file;
                if(!file.Open(strFilePathName,CFile::modeRead)) continue;
                CString fstring = "";
                char *readbuf ;
                readbuf = fstring.GetBuffer(file.GetLength());
                file.Read(readbuf ,file.GetLength());
                file.Close();
                fstring = readbuf;
                CString s1 = "",s2 = "",s3 = "",s4 = "";
                
                int pos1=0,pos2=0,pos3=0,pos4=0;
                while((pos1 = fstring.Find("@")) != -1)
                {
                    s1 = fstring.Left(pos1);
                    fstring.Delete(0,pos1+1);
                    s1.MakeReverse();
                    if((pos2=s1.FindOneOf(flagstr)) != -1)
                    {
                        s2 = s1.Left(pos2);
                        s2.MakeReverse();
                    }
                    if((pos3=fstring.FindOneOf(flagstr)) != -1)
                    {
                        s3 = fstring.Left(pos3);
                    }
                    if(s2!="" && (s3.Find(".")!=-1))
                    {
                        s4 = s2 + "@" + s3;
                        m_list.AddString(s4);
                    }
                }
            }
        }
    }
    finder.Close();
    delete []Word;
}


这有个算法，老鸟门怎么不出来帮忙哦，我想知道正则表达式要怎么写呀，帮帮忙呀