Fedeisas\LaravelMailCssInliner\CssInlinerPlugin::beforeSendPerformed PHP Method

    public function beforeSendPerformed(\Swift_Events_SendEvent $evt)
    {
        $message = $evt->getMessage();
        if ($message->getContentType() === 'text/html' || $message->getContentType() === 'multipart/alternative' && $message->getBody() || $message->getContentType() === 'multipart/mixed' && $message->getBody()) {
            $message->setBody($this->converter->convert($message->getBody(), $this->css));
        }
        foreach ($message->getChildren() as $part) {
            if (strpos($part->getContentType(), 'text/html') === 0) {
                $part->setBody($this->converter->convert($part->getBody(), $this->css));
            }
        }
    }