feat: integrate with MailJet API for newsletter registration

config/packages/messenger.yaml

@@ -13,7 +13,7 @@ framework:
                     max_retries: 3
                     multiplier: 2
             failed: 'doctrine://default?queue_name=failed'
-            # sync: 'sync://'
+            sync: 'sync://'
 
         default_bus: messenger.bus.default
 
@@ -21,7 +21,7 @@ framework:
             messenger.bus.default: []
 
         routing:
-            Symfony\Component\Mailer\Messenger\SendEmailMessage: async
+            Symfony\Component\Mailer\Messenger\SendEmailMessage: sync
             Symfony\Component\Notifier\Message\ChatMessage: async
             Symfony\Component\Notifier\Message\SmsMessage: async