如何在swift mailer setTo函数中传递二维数组值

我得到一个二维数组值作为一个for循环后的结果。值是$chunk[$i][$j]，当我把这个值传递给setTo函数时，错误显示为

Warning: preg_match() expects parameter 2 to be string, array given in H:'xampp 'htdocs'sngmarket'vendor'swiftmailer'swiftmailer'lib'classes'Swift'Mime'Headers 'MailboxHeader.php line 350 .

我如何解决这个问题?这里是我的代码

$query = $em->createQuery("SELECT DISTINCT u.emailaddress FROM AcmeRegistrationBundle:userlist u");
   $grp_emails[] = $query->getResult();
   $chunk = array_chunk($grp_emails, 10);
   $get_chunk_count = count($chunk);
   for($i=0;$i<$get_chunk_count;$i++)
   {
    $count_inside_count = count($chunk[$i]);
      for($j=0;$j<=$count_inside_count;$j++)
      {
        $mails=$chunk[$i][$j];
        $message = 'Swift_Message::newInstance()
          ->setSubject('Hello Email')
          ->setFrom('marketplace@socialnetgate.com')
          ->setTo($mails)
          ->setReturnPath('gowtham@ephronsystems.com')
          ->setBody('Hello World');
          $this->get('mailer')->send($message);
          return array();
      }
   }