diff --git a/README.md b/README.md
index 2e4b0c2b..c826f875 100644
--- a/README.md
+++ b/README.md
@@ -16,7 +16,7 @@ Alternatively, if you want to include the package directly in your website HTML
 
 ```html
 <script type='module' crossorigin="anonymous">
-     import ContentstackLivePreview from 'https://esm.sh/@contentstack/live-preview-utils@4.1.2';
+     import ContentstackLivePreview from 'https://esm.sh/@contentstack/live-preview-utils@4.3.0';
 
      ContentstackLivePreview.init({
         stackDetails: {
@@ -51,7 +51,7 @@ ContentstackLivePreview.init({
 
 MIT License
 
-Copyright © 2021-2025 [Contentstack](https://www.contentstack.com/). All Rights Reserved
+Copyright © 2021-2026 [Contentstack](https://www.contentstack.com/). All Rights Reserved
 
 Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
 
diff --git a/package.json b/package.json
index dfe5c648..dba44d09 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@contentstack/live-preview-utils",
-    "version": "4.1.2",
+    "version": "4.3.0",
     "description": "Contentstack provides the Live Preview SDK to establish a communication channel between the various Contentstack SDKs and your website, transmitting  live changes to the preview pane.",
     "type": "module",
     "types": "dist/legacy/index.d.ts",
diff --git a/src/configManager/__test__/configManager.test.ts b/src/configManager/__test__/configManager.test.ts
index 8d28818b..74f6328d 100644
--- a/src/configManager/__test__/configManager.test.ts
+++ b/src/configManager/__test__/configManager.test.ts
@@ -91,14 +91,14 @@ describe("Config", () => {
 });
 
 describe("config default flags", () => {
-    test("enableLivePreviewOutsideIframe defaults to false in getDefaultConfig", () => {
+    test("enableLivePreviewOutsideIframe defaults to undefined in getDefaultConfig", () => {
         const defaultConfig = getDefaultConfig();
-        expect(defaultConfig.enableLivePreviewOutsideIframe).toBe(false);
+        expect(defaultConfig.enableLivePreviewOutsideIframe).toBeUndefined();
     });
 
-    test("enableLivePreviewOutsideIframe defaults to false in getUserInitData", () => {
+    test("enableLivePreviewOutsideIframe defaults to undefined in getUserInitData", () => {
         const initData = getUserInitData();
-        expect(initData.enableLivePreviewOutsideIframe).toBe(false);
+        expect(initData.enableLivePreviewOutsideIframe).toBeUndefined();
     });
 });
 
diff --git a/src/configManager/__test__/handleUserConfig.test.ts b/src/configManager/__test__/handleUserConfig.test.ts
index 5833cc04..3d61e808 100644
--- a/src/configManager/__test__/handleUserConfig.test.ts
+++ b/src/configManager/__test__/handleUserConfig.test.ts
@@ -423,10 +423,10 @@ describe("handleInitData() - enableLivePreviewOutsideIframe", () => {
         Config.reset();
     });
 
-    test("should default to false when not provided", () => {
+    test("should default to undefined when not provided", () => {
         const initData: Partial<IInitData> = {};
         handleInitData(initData);
-        expect(config.enableLivePreviewOutsideIframe).toBe(false);
+        expect(config.enableLivePreviewOutsideIframe).toBeUndefined();
     });
 
     test("should set to true when provided as true", () => {
diff --git a/src/configManager/config.default.ts b/src/configManager/config.default.ts
index 8a20a7be..5a62351b 100644
--- a/src/configManager/config.default.ts
+++ b/src/configManager/config.default.ts
@@ -39,7 +39,7 @@ export function getUserInitData(): IInitData {
             environment: "",
         },
         runScriptsOnUpdate: false,
-        enableLivePreviewOutsideIframe: false,
+        enableLivePreviewOutsideIframe: undefined,
     };
 }
 
@@ -111,6 +111,6 @@ export function getDefaultConfig(): IConfig {
             },
             payload: [],
         },
-        enableLivePreviewOutsideIframe: false,
+        enableLivePreviewOutsideIframe: undefined,
     };
 }
diff --git a/src/configManager/handleUserConfig.ts b/src/configManager/handleUserConfig.ts
index a964e773..c13a1038 100644
--- a/src/configManager/handleUserConfig.ts
+++ b/src/configManager/handleUserConfig.ts
@@ -121,7 +121,11 @@ export const handleInitData = (initData: Partial<IInitData>): void => {
             "bottom-right",
     })
 
-    Config.set("enableLivePreviewOutsideIframe", initData.enableLivePreviewOutsideIframe ?? config.enableLivePreviewOutsideIframe ?? false);
+    Config.set(
+        "enableLivePreviewOutsideIframe",
+        initData.enableLivePreviewOutsideIframe ??
+            config.enableLivePreviewOutsideIframe
+    );
 
     // client URL params
     handleClientUrlParams(
diff --git a/src/livePreview/eventManager/__test__/postMessageEvent.hooks.test.ts b/src/livePreview/eventManager/__test__/postMessageEvent.hooks.test.ts
index e9f08798..f48b8bcc 100644
--- a/src/livePreview/eventManager/__test__/postMessageEvent.hooks.test.ts
+++ b/src/livePreview/eventManager/__test__/postMessageEvent.hooks.test.ts
@@ -432,6 +432,23 @@ describe("postMessageEvent.hooks", () => {
             });
         });
 
+        it("should omit enableLivePreviewOutsideIframe in INIT payload when config is unset", async () => {
+            mockConfig = {
+                ssr: true,
+                mode: 1,
+                enableLivePreviewOutsideIframe: undefined,
+            };
+            (Config.get as any).mockReturnValue(mockConfig);
+
+            await sendInitializeLivePreviewPostMessageEvent();
+            await Promise.resolve();
+
+            const initPayload = (livePreviewPostMessage?.send as any).mock.calls.at(-1)?.[1];
+            expect(initPayload.config).not.toHaveProperty(
+                "enableLivePreviewOutsideIframe"
+            );
+        });
+
         it("should include enableLivePreviewOutsideIframe=false in INIT payload", async () => {
             mockConfig = {
                 ssr: true, // avoid timers
diff --git a/src/livePreview/eventManager/postMessageEvent.hooks.ts b/src/livePreview/eventManager/postMessageEvent.hooks.ts
index 1ef706d3..9e9f903d 100644
--- a/src/livePreview/eventManager/postMessageEvent.hooks.ts
+++ b/src/livePreview/eventManager/postMessageEvent.hooks.ts
@@ -119,17 +119,29 @@ export function useOnEntryUpdatePostMessageEvent(): void {
 }
 
 export function sendInitializeLivePreviewPostMessageEvent(): void {
+    const config = Config.get();
+    const initConfig: {
+        shouldReload: boolean;
+        href: string;
+        sdkVersion: string | undefined;
+        mode: number;
+        enableLivePreviewOutsideIframe?: boolean;
+    } = {
+        shouldReload: config.ssr,
+        href: window.location.href,
+        sdkVersion: process?.env?.PACKAGE_VERSION,
+        mode: config.mode,
+    };
+
+    if (config.enableLivePreviewOutsideIframe !== undefined) {
+        initConfig.enableLivePreviewOutsideIframe = config.enableLivePreviewOutsideIframe;
+    }
+
     livePreviewPostMessage
         ?.send<LivePreviewInitEventResponse>(
             LIVE_PREVIEW_POST_MESSAGE_EVENTS.INIT,
             {
-                config: {
-                    shouldReload: Config.get().ssr,
-                    href: window.location.href,
-                    sdkVersion: process?.env?.PACKAGE_VERSION,
-                    mode: Config.get().mode,
-                    enableLivePreviewOutsideIframe: Config.get().enableLivePreviewOutsideIframe,
-                },
+                config: initConfig,
             }
         )
         .then((data) => {
diff --git a/src/types/types.ts b/src/types/types.ts
index 76986262..93602ecd 100644
--- a/src/types/types.ts
+++ b/src/types/types.ts
@@ -87,7 +87,7 @@ export declare interface IConfig {
         highlightedElement: HTMLElement | null;
     };
     collab: ICollabConfig["collab"];
-    enableLivePreviewOutsideIframe: boolean;
+    enableLivePreviewOutsideIframe: boolean | undefined;
 }
 
 
@@ -133,7 +133,7 @@ export declare interface IInitData {
     editButton: IConfigEditButton;
     editInVisualBuilderButton: IConfigEditInVisualBuilderButton;
     mode: ILivePreviewMode;
-    enableLivePreviewOutsideIframe: boolean; // default: false
+    enableLivePreviewOutsideIframe: boolean | undefined; // default: undefined
 }
 
 // type PickPartial<T, K extends keyof T> = Partial<Pick<T, K>> & Omit<T, K>;