diff --git a/Classes/Controller/UniversalMessengerController.php b/Classes/Controller/UniversalMessengerController.php
index 4532de5..6ec30ea 100644
--- a/Classes/Controller/UniversalMessengerController.php
+++ b/Classes/Controller/UniversalMessengerController.php
@@ -17,7 +17,11 @@
 use TYPO3\CMS\Backend\Template\ModuleTemplateFactory;
 use TYPO3\CMS\Backend\Utility\BackendUtility;
 use TYPO3\CMS\Core\Authentication\BackendUserAuthentication;
+use TYPO3\CMS\Core\Localization\LanguageService;
 use TYPO3\CMS\Core\Type\Bitmask\Permission;
+use TYPO3\CMS\Core\Type\ContextualFeedbackSeverity;
+use TYPO3\CMS\Core\Utility\GeneralUtility;
+use TYPO3\CMS\Extbase\Http\ForwardResponse;
 use TYPO3\CMS\Extbase\Mvc\Controller\ActionController;
 use TYPO3\CMS\Extbase\Utility\DebuggerUtility;
 
@@ -89,6 +93,14 @@ private function getBackendUserAuthentication(): BackendUserAuthentication
         return $GLOBALS['BE_USER'];
     }
 
+    /**
+     * @return LanguageService
+     */
+    private function getLanguageService(): LanguageService
+    {
+        return $GLOBALS['LANG'];
+    }
+
     /**
      * Returns the module template instance.
      *
@@ -120,7 +132,27 @@ private function moduleResponse(): ResponseInterface
 
         // Show button only at pages matching our page type.
         if ($contentPage['doktype'] !== Configuration::getNewsletterPageDokType()) {
-            return $this->moduleTemplate->renderResponse('Backend/UniversalMessenger.html');
+            $this->moduleTemplate->addFlashMessage(
+                $this->translate('error.page_not_allowed'),
+                'Universal Messenger',
+                ContextualFeedbackSeverity::INFO
+            );
+
+            return new ForwardResponse('error');
+        }
+
+        // Check if backend user is allowed to access this newsletter
+        if (!GeneralUtility::inList(
+            $this->getBackendUserAuthentication()->user['universal_messenger_channels'],
+            $contentPage['universal_messenger_channel']
+        )) {
+            $this->moduleTemplate->addFlashMessage(
+                $this->translate('error.access_not_allowed'),
+                'Universal Messenger',
+                ContextualFeedbackSeverity::ERROR
+            );
+
+            return new ForwardResponse('error');
         }
 
 DebuggerUtility::var_dump($contentPage['title']);
@@ -129,7 +161,21 @@ private function moduleResponse(): ResponseInterface
     }
 
     /**
-     * Shows the textDB entires.
+     * Returns the translated language label for the given identifier.
+     *
+     * @param string $key
+     *
+     * @return string
+     */
+    private function translate(string $key): string
+    {
+        return $this->getLanguageService()->sL(
+            'LLL:EXT:nrc_universal_messenger/Resources/Private/Language/locallang.xlf:' . $key
+        );
+    }
+
+    /**
+     * The main entry point.
      *
      * @return ResponseInterface
      */
@@ -139,4 +185,14 @@ public function indexAction(): ResponseInterface
 
         return $this->moduleResponse();
     }
+
+    /**
+     * The error entry point.
+     *
+     * @return ResponseInterface
+     */
+    public function errorAction(): ResponseInterface
+    {
+        return $this->moduleTemplate->renderResponse('Backend/UniversalMessenger.html');
+    }
 }
diff --git a/Resources/Private/Language/de.locallang.xlf b/Resources/Private/Language/de.locallang.xlf
index 2efc4c3..b043361 100644
--- a/Resources/Private/Language/de.locallang.xlf
+++ b/Resources/Private/Language/de.locallang.xlf
@@ -8,6 +8,14 @@
                 <target>Universal Messenger</target>
             </trans-unit>
 
+            <!-- errors -->
+            <trans-unit id="error.page_not_allowed">
+                <target>Bitte wählen Sie eine Seite mit dem Seiten-Typ "Newsletter" aus.</target>
+            </trans-unit>
+            <trans-unit id="error.access_not_allowed">
+                <target>Sie verfügen nicht über die notwendigen Rechte, um diesen Newsletter zu versenden.</target>
+            </trans-unit>
+
             <!-- be_users -->
             <trans-unit id="be_users.universal_messenger_channels">
                 <target>Newsletter-Kanäle</target>
diff --git a/Resources/Private/Language/locallang.xlf b/Resources/Private/Language/locallang.xlf
index 99ab571..5606f68 100644
--- a/Resources/Private/Language/locallang.xlf
+++ b/Resources/Private/Language/locallang.xlf
@@ -8,12 +8,20 @@
                 <source>Universal Messenger</source>
             </trans-unit>
 
+            <!-- errors -->
+            <trans-unit id="error.page_not_allowed">
+                <source>Please select a page with the page type "Newsletter".</source>
+            </trans-unit>
+            <trans-unit id="error.access_not_allowed">
+                <source>You do not have the necessary rights to send this newsletter.</source>
+            </trans-unit>
+
             <!-- be_users -->
             <trans-unit id="be_users.universal_messenger_channels">
-                <target>Newsletter channels</target>
+                <source>Newsletter channels</source>
             </trans-unit>
             <trans-unit id="be_users.universal_messenger_channels.description">
-                <target>Here select the newsletter channels for which this user is allowed to send newsletters.</target>
+                <source>Here select the newsletter channels for which this user is allowed to send newsletters.</source>
             </trans-unit>
 
             <!-- pages -->