diff --git a/assets/js/src/public.jsx b/assets/js/src/public.jsx
index f80a8756e0..c49e318c95 100644
--- a/assets/js/src/public.jsx
+++ b/assets/js/src/public.jsx
@@ -1,11 +1,34 @@
 import MailPoet from 'mailpoet';
 import jQuery from 'jquery';
 import Cookies from 'js-cookie';
-import 'parsleyjs';
+import Parsley from 'parsleyjs';
 
 const exitIntentEvent = 'mouseleave.mailpoet.form-exit-intent';
 
 jQuery(($) => {
+  Parsley.addValidator('names', {
+    requirementType: ['string', 'string'],
+    validateString: (value, errorBrackets, errorURL) => {
+      // Name can't contain angle brackets - https://mailpoet.atlassian.net/browse/MAILPOET-3408
+      const bracketsExpression = /[><]+/gi;
+      const bracketsRegex = new RegExp(bracketsExpression);
+      if (value.match(bracketsRegex)) {
+        return $.Deferred().reject(errorBrackets);
+      }
+      // Name can't contain URL - https://mailpoet.atlassian.net/browse/MAILPOET-3786
+      const urlExpression = /https?:\/\/(www\.)?(.+)\.(.+)/gi;
+      const urlRegex = new RegExp(urlExpression);
+      if (value.match(urlRegex)) {
+        return $.Deferred().reject(errorURL);
+      }
+
+      return true;
+    },
+    messages: {
+      en: 'Please specify a valid name',
+    },
+  });
+
   function renderCaptcha(element, iteration) {
     if (!window.recaptcha || !window.grecaptcha.ready) {
       if (iteration < 20) {
diff --git a/lib/Form/Block/BlockRendererHelper.php b/lib/Form/Block/BlockRendererHelper.php
index 24806af1f6..38950937bd 100644
--- a/lib/Form/Block/BlockRendererHelper.php
+++ b/lib/Form/Block/BlockRendererHelper.php
@@ -38,8 +38,13 @@ class BlockRendererHelper {
     }
 
     if (($blockId === 'first_name') || ($blockId === 'last_name')) {
-      $rules['pattern'] = "^[^><]*$";
-      $rules['error-message'] = __('Please specify a valid name', 'mailpoet');
+      $errorMessages = [
+        __('Please specify a valid name', 'mailpoet'),
+        __('Addresses in names are not permitted, please add your name instead.', 'mailpoet'),
+      ];
+      $rules['names'] = '[' . implode(',', array_map(function (string $errorMessage): string {
+        return htmlspecialchars((string)json_encode($errorMessage), ENT_QUOTES);
+      }, $errorMessages)) . ']';
     }
 
     if ($blockId === 'segments') {
@@ -85,7 +90,12 @@ class BlockRendererHelper {
         if (is_bool($value)) {
           $value = ($value) ? 'true' : 'false';
         }
-        $validation[] = 'data-parsley-' . $rule . '="' . $value . '"';
+        // We need to use single quotes because we need to pass array of strings as a parameter for custom validation
+        if ($rule === 'names') {
+          $validation[] = 'data-parsley-' . $rule . '=\'' . $value . '\'';
+        } else {
+          $validation[] = 'data-parsley-' . $rule . '="' . $value . '"';
+        }
       }
     }
     return join(' ', $validation);