Symfony 4 - Problem sending email after change my DNS - api

Question

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Hey, my client change her DNS (like that : xxx-dns.com to dns.com) and this is ok, except one problem.. In react native app, I have contact form for send message to pro "partner", and this pro partner are in the process of switching their emails from xxx-dns.com to dns.com.
BUT the contact form provide by SwitchMailer doesn't work with the new DNS, I have check all configuration files, same for the server, the controller is (I think) ok.
Please help me, it's been a week
I have var_dump() all information in my controller, check api endpoint, navigate into my server and check configuration files.
This is my contact controller :
namespace App\Controller;
use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\Routing\Annotation\Route;
use Symfony\Component\Security\Core\Authentication\Token\Storage\TokenStorageInterface;
use Twig\Environment as Twig;
class ContactController extends AbstractController
{
/**
* #var string
*/
private $mailFrom;
/**
* #var string
*/
private $backUrl;
private $tokenStorage;
public function __construct(string $mailFrom, string $backUrl, TokenStorageInterface $tokenStorage)
{
$this->mailFrom = $mailFrom;
$this->backUrl = $backUrl;
$this->tokenStorage = $tokenStorage;
}
/**
* #Route("/contact", name="app_send_contact")
*/
public function sendAction(\Swift_Mailer $mailer, Twig $twig, Request $request)
{
// Retrieve user
$currentUser = $this->tokenStorage->getToken()->getUser();
if (!$currentUser) {
return $this->json(array('success' => false, 'message' => 'Utilisateur introuvable.'));
}
// Prepare parameters
$contactObject = $request->request->get('object');
$contactMessage = $request->request->get('message');
// Retrieve establishment
$establishment = $currentUser->getEstablishments()->first();
if (!$establishment) {
return $this->json(array('success' => false, 'message' => 'Etablissement introuvable.'));
}
// Prepare mail
$mailTitle = $currentUser->getFirstname() . ' ' . $currentUser->getLastname() . ' vous a envoyé un message : ' . $contactObject;
// Send mail to establishment
$message = (new \Swift_Message($mailTitle))
->setFrom($this->mailFrom)
->setTo($establishment->getEmail())
->setReplyTo($currentUser->getEmail(), $currentUser->getFirstname() . ' ' . $currentUser->getLastname())
->setBody(
$twig->render(
'emails/contact.html.twig',
array(
'user' => $currentUser,
'establishment' => $establishment,
'contact_object' => $contactObject,
'contact_message' => $contactMessage,
'back_url' => $this->backUrl,
)
),
'text/html'
);
$mailer->send($message);
// Prepare mail
$mailTitle = 'Confirmation de demande de contact';
// Send mail to parent
$message = (new \Swift_Message($mailTitle))
->setFrom($this->mailFrom)
->setTo($currentUser->getEmail())
->setBody(
$twig->render(
'emails/contact_confirmation.html.twig',
array(
'user' => $currentUser,
'establishment' => $establishment,
'contact_object' => $contactObject,
'contact_message' => $contactMessage,
'back_url' => $this->backUrl,
)
),
'text/html'
);
$mailer->send($message);
return $this->json(array('success' => true));
}
}```