my $email_s = Email::Simple->create(
  header => [
    From    => 'xxx@xxx.com',
    Subject => "test hi",
	'Content-Type' => 'text/html', 
  ],
  body => $message_s,
);

$email_s->header_set('bcc');
sendmail($email_s, { transport => $transport, to => [$tostring] });