public function sendRawEmail($raw_data, $dest=[]) 
    {
        //force base64 encoding on v2 Api
        if ($this->isVersion2() && base64_decode($raw_data, true)===false)
            $raw_data = base64_encode($raw_data);
        
        $mail = [
            //'FromArn' => '<string>',
            'Source'                => $this->from, // REQUIRED
            //'SourceArn' => '<string>',
            'RawMessage'            => ['Data' => $raw_data],
            //'ReturnPathArn' => '<string>',
        ];

        // override destinations
        if ($dest)
            $mail['Destinations'] = $dest;
        
        if ($this->tags)
            $mail['Tags'] = $this->buildTags();

        return $this->invokeMethod("sendRawEmail", $mail, true);
    }