может тут что то не так?
$mail = new Mail($this->config->get('config_mail_engine'));
$mail->parameter = $this->config->get('config_mail_parameter');
$mail->smtp_hostname = $this->config->get('config_mail_smtp_hostname');
$mail->smtp_username = $this->config->get('config_mail_smtp_username');
$mail->smtp_password = html_entity_decode($this->config->get('config_mail_smtp_password'), ENT_QUOTES, 'UTF-8');
$mail->smtp_port = $this->config->get('config_mail_smtp_port');
$mail->smtp_timeout = $this->config->get('config_mail_smtp_timeout');
$mail->setTo($order_info['email']);
$mail->setFrom($from);
$mail->setSender(html_entity_decode($order_info['store_name'], ENT_QUOTES, 'UTF-8'));
$mail->setSubject(html_entity_decode(sprintf($language->get('text_subject'), $order_info['store_name'], $order_info['order_id']), ENT_QUOTES, 'UTF-8'));
$mail->setHtml($this->load->view('mail/order_add', $data));
$mail->send();