--- web/modules/contrib/mailsystem/src/Form/AdminForm.php	2026-01-05 11:10:02
+++ /tmp/AdminForm.php.new	2026-01-05 11:07:15
@@ -359,16 +359,12 @@
    */
   protected function getModulesList() {
     $list = [];
-    if (method_exists($this->moduleHandler, 'invokeAllWith')) {
-      $this->moduleHandler->invokeAllWith('mail', function (callable $hook, string $module) use (&$list) {
-        $list[$module] = $this->moduleHandler->getName($module);
-      });
-    }
-    else {
-      foreach ($this->moduleHandler->getImplementations('mail') as $module) {
-        $list[$module] = $this->moduleHandler->getName($module);
-      }
-    }
+    $module_extension_list = \Drupal::service('extension.list.module');
+
+    $this->moduleHandler->invokeAllWith('mail', function (callable $hook, string $module) use (&$list, $module_extension_list) {
+      $list[$module] = $module_extension_list->getName($module);
+    });
+
     asort($list);
     return $list;
   }
--- web/modules/contrib/mailsystem/tests/modules/mailsystem_test/mailsystem_test.module	2026-01-05 11:10:02
+++ /tmp/mailsystem_test.module.new	2026-01-05 11:07:23
@@ -18,7 +18,7 @@
       $username = ['#theme' => 'username', '#account' => $account];

       $message['subject'] = new TranslatableMarkup('Testing mail theme.');
-      $message['body'][] = (string) \Drupal::service('renderer')->renderPlain($username);
+      $message['body'][] = (string) \Drupal::service('renderer')->renderInIsolation($username);
       break;
   }
 }