public function getEmailContent()
    {
        $mailContent = '';
        // Text content
        if (!empty($this->textContent)) {
            $mailContent .= '--' . $this->boundary . PHP_EOL;
            $mailContent .= 'Content-Type: text/plain; charset="' . $this->charset . '"' . PHP_EOL;
            $mailContent .= 'Content-Transfer-Encoding: 8bit' . PHP_EOL . PHP_EOL;
            $mailContent .= $this->textContent . PHP_EOL . PHP_EOL;
        }
        // Html content
        if (!empty($this->htmlContent)) {
            $mailContent .= '--' . $this->boundary . PHP_EOL;
            $mailContent .= 'Content-Type: text/html; charset="' . $this->charset . '"' . PHP_EOL;
            $mailContent .= 'Content-Transfer-Encoding: 8bit' . PHP_EOL . PHP_EOL;
            $mailContent .= $this->htmlContent . PHP_EOL . PHP_EOL;
        }
        $mailContent .= '--' . $this->boundary . '--';
        return $mailContent;
    }