关于邮件解析(源码)

    存储邮件信息的结构：

    struct ContentHeader{
                            int         nType;//=(1)0 text/plain, =(1)1 text/html, =(1)2 maybe attach
                            AnsiString  strTransferEncoding;
                            AnsiString  strContent;
                            AnsiString  strFileName;//for attachment
                        };

    处理每一行的函数，处理完成存入结构体ContehtHeader,并存入链表CHList( TList* )

    void __fastcall TRecvMailThread::DealLine(char* line, int len)
    {
            int pos;
        AnsiString strLine( line );
        AnsiString strTemp( line );
        strLine = strLine.LowerCase();
        switch( nItemKind )
        {
        case 0 :
            if( strLine == "" && nItems >= 1 )//第一部分结束
            {
                nItemKind = 1;//进入下一部分
                break;
            }
            if( ( pos = strLine.AnsiPos( "from:" ) ) == 1 )
            {
                if( strFrom == "" )
                {
                    strFrom = strTemp.SubString( pos + 5, len - pos - 4 );
                    if( strFrom[ 1 ] == 0x20 )
                        strFrom = strFrom.SubString( 2, strFrom.Length() - 1 );
                    nItems ++;
                }
            }
            else if( ( pos = strLine.AnsiPos( "to:" ) ) == 1 )
            {
                if( strTo  == "" )
                {
                    strTo = strTemp.SubString( pos + 3, len - pos - 2 );
                    if( strTo[ 1 ] == 0x20 )
                        strTo = strTo.SubString( 2, strTo.Length() - 1 );
                    nItems ++;
                }
            }
            else if( ( pos = strLine.AnsiPos( "subject:" ) ) == 1 )
            {
                if( strSubject == "" )
                {
                    strSubject = strTemp.SubString( pos + 8, len - pos - 7 );
                    if( strSubject[ 1 ] == 0x20 )
                        strSubject = strSubject.SubString( 2, strSubject.Length() - 1 );
                    nItems ++;
                }
            }
            else if( ( pos = strLine.AnsiPos( "content-type: multipart" ) ) != 0 )
            {
                if( ( pos = strLine.AnsiPos( "boundary=" ) ) != 0 )
                {
                    strNormalBoundary = strTemp.SubString( pos + 9, len - pos - 8 );
                    if( strNormalBoundary[ 1 ] == '\"' )
                        strNormalBoundary = strNormalBoundary.SubString( 2, strNormalBoundary.Length() - 2 );
                    bBoundary = true;
                }
            }
            else if( ( pos = strLine.AnsiPos( "boundary=" ) ) != 0 )
            {
                strNormalBoundary = strTemp.SubString( pos + 9, len - pos - 8 );
                if( strNormalBoundary[ 1 ] == '\"' )
                    strNormalBoundary = strNormalBoundary.SubString( 2, strNormalBoundary.Length() - 2 );
                bBoundary = true;
            }
            else if( ( pos = strLine.AnsiPos( "content-type: text/plain" ) ) != 0 )
            {
                nTextKind = 0;
                pCH->nType = 0;
            }
            else if( ( pos = strLine.AnsiPos( "content-type: text/html" ) ) != 0 )
            {
                nTextKind = 1;
                pCH->nType = 1;
            }
            else if( ( pos = strLine.AnsiPos( "content-transfer-encoding: " ) ) != 0 )
            {
                strTempEncode = strLine.SubString( pos + 27, len - pos - 26 );
                pCH->strTransferEncoding = strTempEncode;
            }
        break;
        case 1 :
            if( bBoundary )
            {
                if( strTemp.AnsiPos( strNormalBoundary ) != 0 )
                {
                    file://找到边界，
                    nItemKind = 2;
                    nItems = 0;
                    bBoundary = false;
                }
            }
            else
            {
                file://没有边界，以下为邮件正文部分，至 "." 结束
                pCH->strContent = strTemp;
                nItemKind = 111;
            }
        break;
        case 111 :
            if( strLine != "." )
            {
                pCH->strContent += strTemp;
                pCH->strContent += "\r\n";
            }
            else
            {
                CHList->Add( pCH );
                nItemKind = ALL_READY;
            }
        break;
        case 2 :
            file://在此查找Content-Type, Content-Transfer-Encoding, boundary, Content-Disposition等
            //.........
            if( strLine == "" && nItems >= 1 )
            {
                file://进入下一部分
                nItemKind = 3;
                nItems = 0;
                break;
            }
            if( ( pos = strLine.AnsiPos( "content-type:" ) ) != 0 )
            {
                nItems ++;
                if( strLine.AnsiPos( "multipart/" ) != 0 )
                {
                    if( ( pos = strLine.AnsiPos( "boundary=" ) ) != 0 )
                    {
                        strExpandBoundary = strTemp.SubString( pos + 9, len - pos - 8 );
                        if( strExpandBoundary[ 1 ] == '\"' )
                            strExpandBoundary = strExpandBoundary.SubString( 2, strExpandBoundary.Length() - 2 );
                        bBoundary = true;
                    }
                    nItemKind = 222;
                    break;
                }
                if( strLine.AnsiPos( "text/plain" ) != 0 )
                    nTextKind = 0;
                else if( strLine.AnsiPos( "text/html" ) != 0 )
                    nTextKind = 1;
                else
                    nTextKind = 2;
                pCH->nType = nTextKind;
            }
            else if( ( pos = strLine.AnsiPos( "content-transfer-encoding:" ) ) != 0 )
            {
                nItems ++;
                pCH->strTransferEncoding = strLine.SubString( pos + 27, len - pos - 26 );
            }
            else if( strLine.AnsiPos( "content-disposition:" ) != 0 )
            {