diff --git a/apps/emails-and-messages/src/pages/api/register.ts b/apps/emails-and-messages/src/pages/api/register.ts
index 796ec03..382f71a 100644
--- a/apps/emails-and-messages/src/pages/api/register.ts
+++ b/apps/emails-and-messages/src/pages/api/register.ts
@@ -2,6 +2,8 @@ import { createAppRegisterHandler } from "@saleor/app-sdk/handlers/next";
 
 import { saleorApp } from "../../saleor-app";
 
+const allowedUrlsPattern = process.env.ALLOWED_DOMAIN_PATTERN;
+
 /**
  * Required endpoint, called by Saleor to install app.
  * It will exchange tokens with app, so saleorApp.apl will contain token
@@ -9,17 +11,14 @@ import { saleorApp } from "../../saleor-app";
 export default createAppRegisterHandler({
   apl: saleorApp.apl,
   allowedSaleorUrls: [
-    /**
-     * You may want your app to work only for certain Saleor instances.
-     *
-     * Your app can work for every Saleor that installs it, but you can
-     * limit it here
-     *
-     * By default, every url is allowed.
-     *
-     * URL should be a full graphQL address, usually starting with https:// and ending with /graphql/
-     *
-     * Alternatively pass a function
-     */
+    (url) => {
+      if (allowedUrlsPattern) {
+        const regex = new RegExp(allowedUrlsPattern);
+
+        return regex.test(url);
+      }
+
+      return true;
+    },
   ],
 });