[all hosts] (Office 2016) Address Office 2016 and Office 2019 reaching end of support (#5463)

* Address Office 2016 and Office 2019 reaching end of support

* Add redirects

* Apply suggestions from code review

Co-authored-by: Rick Kirkham <Rick-Kirkham@users.noreply.github.com>

* PR feedback

* Remove distinctions for the Chromium-based Edge

* Fix links

* Remove add-in commands build numbers

* Apply suggestions from code review

Co-authored-by: Elizabeth Samuel <elizs@microsoft.com>

---------

Co-authored-by: Rick Kirkham <Rick-Kirkham@users.noreply.github.com>
Co-authored-by: Elizabeth Samuel <elizs@microsoft.com>

Author: 3 people

.markdownlint.json

@@ -1,4 +1,5 @@
 {
+  "MD013": false,
   "MD025": false,
   "MD033": {
     "allowed_elements": ["kbd"]

.openpublishing.redirection.json

@@ -1369,6 +1369,26 @@
        {
             "source_path": "docs/outlook/turn-exchange-tokens-on-off.md",
             "redirect_url": "/office/dev/add-ins/develop/faq-legacy-exchange-tokens"
+        },
+        {
+            "source_path": "docs/develop/support-ie-11.md",
+            "redirect_url": "/office/dev/add-ins/concepts/browsers-used-by-office-web-add-ins"
+        },
+        {
+            "source_path": "docs/testing/debug-add-ins-using-devtools-edge-legacy.md",
+            "redirect_url": "/office/dev/add-ins/testing/debug-add-ins-overview"
+        },
+        {
+            "source_path": "docs/testing/debug-add-ins-using-f12-tools-ie.md",
+            "redirect_url": "/office/dev/add-ins/testing/debug-add-ins-overview"
+        },
+        {
+            "source_path": "docs/testing/ie-11-testing.md",
+            "redirect_url": "/office/dev/add-ins/concepts/browsers-used-by-office-web-add-ins"
+        },
+        {
+            "source_path": "docs/design/add-in-icons-fresh.md",
+            "redirect_url": "/office/dev/add-ins/design/add-in-icons"
         }
     ]
 }

docs/concepts/add-in-development-best-practices.md

@@ -2,7 +2,7 @@
 title: Best practices for developing Office Add-ins
 description: Apply the best practices when developing Office Add-ins.
 ms.topic: best-practice
-ms.date: 07/28/2025
+ms.date: 11/06/2025
 ms.localizationpriority: medium
 ---
 
@@ -153,10 +153,6 @@ Ready to share your add-in with the world? Here's how to get started.
 > [!IMPORTANT]
 > [!INCLUDE [Microsoft Marketplace enterprise info](../includes/appsource-enterprise.md)]
 
-## Support older Microsoft webviews and Office versions (recommended but not required)
-
-See [Support older Microsoft webviews and Office versions](../develop/support-ie-11.md).
-
 ## See also
 
 - [Office Add-ins platform overview](../overview/office-add-ins.md)

docs/concepts/browsers-used-by-office-web-add-ins.md

@@ -1,7 +1,7 @@
 ---
 title: Requirements for running Office Add-ins
 description: Learn about the client and server requirements that an end user needs to run Office Add-ins.
-ms.date: 08/13/2025
+ms.date: 11/06/2025
 ms.localizationpriority: medium
 ---
 
@@ -47,13 +47,7 @@ The following software is required for developing an Office Add-in for the suppo
   If you have a valid Microsoft 365 subscription and you don't have access to the Office client, you can [download and install the latest version of Office](https://support.microsoft.com/office/4414eaaf-0478-48be-9c42-23adc4716658).
 
 - Microsoft Edge must be installed, but doesn't have to be the default browser. To support Office Add-ins, the Office client that acts as host uses webview components that are part of Microsoft Edge.
-
-  > [!NOTE]
-  >
-  > - Strictly speaking, it's possible to develop add-ins on a machine that has Internet Explorer 11 (IE11) installed, but not Microsoft Edge. However, IE11 is used to run add-ins only on certain older combinations of Windows and Office versions. See [Browsers and webview controls used by Office Add-ins](browsers-used-by-office-web-add-ins.md) for more details. We don't recommend using such old environments as your primary add-in development environment. However, if you're likely to have customers of your add-in that are working in these older combinations, we recommend that you support the Trident webview that's provided by Internet Explorer. For more information, see [Support older Microsoft webviews and Office versions](../develop/support-ie-11.md).
-  > - Internet Explorer's Enhanced Security Configuration (ESC) must be turned off for Office Web Add-ins to work. If you are using a Windows Server computer as your client when developing add-ins, note that ESC is turned on by default in Windows Server.
-
-- One of the following as the default browser: Internet Explorer 11, or the latest version of Microsoft Edge, Chrome, Firefox, or Safari (Mac OS).
+- One of the following as the default browser: Microsoft Edge, Chrome, Firefox, or Safari (Mac OS).
 - An HTML and JavaScript editor such as [Visual Studio Code](https://code.visualstudio.com/), [Visual Studio and the Microsoft Developer Tools](https://www.visualstudio.com/features/office-tools-vs), or non-Microsoft web development tool.
 
 ## Client requirements: OS X desktop
@@ -68,7 +62,7 @@ The following are the minimum client versions of Office on Mac that support Offi
 
 ## Client requirements: Browser support for Office web clients and SharePoint
 
-Any browser, except Internet Explorer, that supports ECMAScript 5.1, HTML5, and CSS3, such as Microsoft Edge, Chrome, Firefox, or Safari (Mac OS).
+Any browser that supports ECMAScript 5.1, HTML5, and CSS3, such as Microsoft Edge, Chrome, Firefox, or Safari (Mac OS).
 
 ## Client requirements: Non-Windows smartphone and tablet
 

docs/concepts/requirements-for-running-office-add-ins.md

@@ -128,9 +128,9 @@ You can specify a custom contextual tab; that is, a tab that is only visible on
 Add-in commands are currently supported on the following platforms, except for limitations specified in the subsections of [Command capabilities](#command-capabilities) earlier.
 
 - Office on the web
-- Office on Windows (Version 1604 (Build 6769.2000) or later, connected to a Microsoft 365 subscription)
-- Office on Mac (Version 15.33 (17040900) or later, connected to a Microsoft 365 subscription)
-- Perpetual Office 2019 or later on Windows or on Mac
+- Office on Windows connected to a Microsoft 365 subscription
+- Office on Mac connected to a Microsoft 365 subscription
+- Perpetual Office 2021 or later on Windows or on Mac
 
 > [!NOTE]
 > For information about support in Outlook, see [Outlook support notes](../develop/create-addin-commands.md#outlook-support-notes).

docs/design/add-in-commands.md

@@ -1,50 +1,46 @@
 ---
 title: Monoline style icon guidelines for Office Add-ins
 description: Guidelines for using Monoline style icons in Office Add-ins.
-ms.date: 02/12/2025
+ms.date: 11/06/2025
 ms.topic: best-practice
 ms.localizationpriority: medium
 ---
 
 # Monoline style icon guidelines for Office Add-ins
 
-Monoline style iconography are used in Office apps. If you'd prefer that your icons match the Fresh style of perpetual Office 2016 and later, see [Fresh style icon guidelines for Office Add-ins](add-in-icons-fresh.md).
-
-## Office Monoline visual style
-
 The goal of the Monoline style to have consistent, clear, and accessible iconography to communicate action and features with simple visuals, ensure the icons are accessible to all users, and have a style that is consistent with those used elsewhere in Windows.
 
 The following guidelines are for 3rd party developers who want to create icons for features that will be consistent with the icons already present Office products.
 
-### Design principles
+## Design principles
 
 - Simple, clean, clear.
 - Contain only necessary elements.
 - Inspired by Windows icon style.
 - Accessible to all users.
 
-#### Convey meaning
+### Convey meaning
 
 - Use descriptive elements such as a page to represent a document or an envelope to represent mail.
 - Use the same element to represent the same concept. For example, mail is always represented by an envelope, not a stamp.
 - Use a core metaphor during concept development.
 
-#### Reduction of elements
+### Reduction of elements
 
 - Reduce the icon to its core meaning, using only elements that are essential to the metaphor.
 - Limit the number of elements in an icon to two, regardless of icon size.
 
-#### Consistency
+### Consistency
 
 Sizes, arrangement, and color of icons should be consistent.
 
-#### Styling
+### Styling
 
-##### Perspective
+#### Perspective
 
 Monoline icons are forward-facing by default. Certain elements that require perspective and/or rotation, such as a cube, are allowed, but exceptions should be kept to a minimum.
 
-##### Embellishment
+#### Embellishment
 
 Monoline is a clean minimal style. Everything uses flat color, which means there are no gradients, textures, or light sources.