public function inlineAttachment($name, $content)
    {
        if (!is_string($content) && (!is_resource($content) || get_resource_type($content) != 'stream')) {
            throw new Exception\InvalidArgumentException(
                sprintf("Attachment content must be either string or stream, %s passed")
            );
        }
        
        $this->attachments[$name] = [
            'content' => $content,
            'inline'  => true
        ];
    }