public function setBcc($bcc)
    {
        if ($bcc instanceof Email) {
            $bcc = [$bcc];
        }

        foreach ($bcc as $email) {
            if (!$email instanceof Email) {
                throw new MailerException('Email must be an instance of \Webiny\Component\Mailer\Email.');
            }
            $this->addBcc($email);
        }

        return $this;
    }