diff --git a/lib/Form/FormMessageController.php b/lib/Form/FormMessageController.php
new file mode 100644
index 0000000000..2105818c38
--- /dev/null
+++ b/lib/Form/FormMessageController.php
@@ -0,0 +1,48 @@
+<?php declare(strict_types = 1);
+
+namespace MailPoet\Form;
+
+use MailPoet\Entities\FormEntity;
+use MailPoet\Settings\SettingsController;
+
+class FormMessageController {
+  /** @var FormsRepository */
+  private $formsRepository;
+
+  /** @var SettingsController */
+  private $settings;
+
+  public function __construct(
+    FormsRepository $formsRepository,
+    SettingsController $settingsController
+  ) {
+    $this->formsRepository = $formsRepository;
+    $this->settings = $settingsController;
+  }
+
+  public function updateSuccessMessages(): void {
+    $rightMessage = $this->getDefaultSuccessMessage();
+    $wrongMessage = (
+    $rightMessage === __('Check your inbox or spam folder to confirm your subscription.', 'mailpoet')
+      ? __('You’ve been successfully subscribed to our newsletter!', 'mailpoet')
+      : __('Check your inbox or spam folder to confirm your subscription.', 'mailpoet')
+    );
+    /** @var FormEntity[] $forms */
+    $forms = $this->formsRepository->findAll();
+    foreach ($forms as $form) {
+      $settings = $form->getSettings();
+      if (isset($settings['success_message']) && $settings['success_message'] === $wrongMessage) {
+        $settings['success_message'] = $rightMessage;
+        $form->setSettings($settings);
+        $this->formsRepository->flush();
+      }
+    }
+  }
+
+  public function getDefaultSuccessMessage(): string {
+    if ($this->settings->get('signup_confirmation.enabled')) {
+      return __('Check your inbox or spam folder to confirm your subscription.', 'mailpoet');
+    }
+    return __('You’ve been successfully subscribed to our newsletter!', 'mailpoet');
+  }
+}
diff --git a/tests/integration/Form/FormMessageControllerTest.php b/tests/integration/Form/FormMessageControllerTest.php
new file mode 100644
index 0000000000..4705482fb1
--- /dev/null
+++ b/tests/integration/Form/FormMessageControllerTest.php
@@ -0,0 +1,63 @@
+<?php declare(strict_types = 1);
+
+namespace MailPoet\Form;
+
+use MailPoet\Entities\FormEntity;
+use MailPoet\Settings\SettingsController;
+
+class FormMessageControllerTest extends \MailPoetTest {
+  /** @var FormMessageController */
+  private $controller;
+
+  /** @var SettingsController */
+  private $settings;
+
+  /** @var FormsRepository */
+  private $formsRepository;
+
+  public function _before() {
+    parent::_before();
+    $this->controller = $this->diContainer->get(FormMessageController::class);
+    $this->settings = $this->diContainer->get(SettingsController::class);
+    $this->formsRepository = $this->diContainer->get(FormsRepository::class);
+  }
+
+  public function testItReturnsCorrectSuccessMessage(): void {
+    $this->settings->set('signup_confirmation.enabled', 1);
+    expect($this->controller->getDefaultSuccessMessage())->equals(__('Check your inbox or spam folder to confirm your subscription.', 'mailpoet'));
+    $this->settings->set('signup_confirmation.enabled', 0);
+    expect($this->controller->getDefaultSuccessMessage())->equals(__('You’ve been successfully subscribed to our newsletter!', 'mailpoet'));
+  }
+
+  public function testItUpdatesSuccessMessagesForForms(): void {
+    $this->settings->set('signup_confirmation.enabled', 1);
+    $form = new FormEntity('test form');
+    $form->setSettings(['success_message' => __('Check your inbox or spam folder to confirm your subscription.', 'mailpoet')]);
+    $this->entityManager->persist($form);
+    $this->entityManager->flush();
+
+    $this->settings->set('signup_confirmation.enabled', 0);
+    $this->controller->updateSuccessMessages();
+    $forms = $this->formsRepository->findAll();
+    expect($forms)->count(1);
+    foreach ($forms as $form) {
+      expect($form->getSettings()['success_message'] ?? null)->equals(__('You’ve been successfully subscribed to our newsletter!', 'mailpoet'));
+    }
+
+    $this->settings->set('signup_confirmation.enabled', 1);
+    $this->controller->updateSuccessMessages();
+    $forms = $this->formsRepository->findAll();
+    expect($forms)->count(1);
+    foreach ($forms as $form) {
+      expect($form->getSettings()['success_message'] ?? null)->equals(__('Check your inbox or spam folder to confirm your subscription.', 'mailpoet'));
+    }
+  }
+
+  private function clear() {
+    $this->truncateEntity(FormEntity::class);
+  }
+
+  public function _after() {
+    $this->clear();
+  }
+}