public function getNextLine()
    {
        if ( $this->currentMessagePosition === 0 )
        {
            $this->nextMail();
        }
        if ( $this->hasMoreMailData )
        {
            $data = fgets( $this->fh );
            if ( feof( $this->fh ) || substr( $data, 0, 5 ) === "From " )
            {
                $this->hasMoreMailData = false;

                return null;
            }
            return $data;
        }
        return null;
    }