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Guidance on IE11 Support and User Detection for Outlook Add-in Migration to Angular 19

Singh Rana, Devendra 20 Reputation points
2025-08-21T16:59:46.6866667+00:00

We are in the process of migrating our Outlook Add-in from AngularJS to Angular 19. Since Angular 12 and later versions have dropped support for IE11, we want to ensure a smooth transition for our users.

Currently, we have checked for IE11 users on Outlook 2016 PCs through two approaches:

  1. User agent (UA) parsing in our add-in — this shows zero active users on IE11.
  2. Office.js API (Office.context.mailbox.diagnostics.hostVersion) to detect Office version — some users still have Outlook 2016 on PC.

Given that Outlook 2016 uses IE11 as the embedded webview for add-ins, we are uncertain which data source we should treat as the source of truth for identifying IE11 users.

  1. Do we have any recommended way to detect IE11 usage reliably in Outlook add-ins today?
  2. Is there any workaround to support IE11 compatibility when migrating to Angular 19 or later versions?
  3. Are there any official APIs or best practices for handling legacy IE11 environments in modern Angular-based Office Add-ins?

Any guidance or recommendations on this topic would be greatly appreciated.

Thank you!

Microsoft 365 and Office | Development | Office JavaScript API
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  1. Teddie-D 3,920 Reputation points Microsoft External Staff Moderator
    2025-08-22T04:42:25.4766667+00:00

    Hi @Singh Rana, Devendra 

    Thank you for posting your question in the Microsoft Q&A forum. 
    According to this Microsoft documentation Support older Microsoft webviews and Office versions - Office Add-ins | Microsoft Learn. You can use window.navigator.userAgent to detect the embedded webview engine. Although IE11 is disabled for UI access in Windows 10/11, its Trident engine is still callable by Office desktop clients like Outlook 2016. This makes user agent detection a valid method for identifying legacy environments. 
    While there are no dedicated APIs for IE11 detection, you may consider using transpilers or polyfills to support older JavaScript features as a workaround. However, Angular 12 and later versions no longer support IE11 officially. Therefore, the best path forward is to gradually deprecate IE11 support and transition to modern WebView2-based experiences, which offer better performance and security.  Since I'm not familiar with the Angular environment and the documentation doesn't explicitly confirm compatibility with Angular, I recommend giving it a try cautiously. To avoid providing an inaccurate solution or causing unnecessary support delays, it would be best to start a new thread in the Angular Community. They may offer more targeted guidance and help ensure the approach aligns with best practices for Angular-based Outlook Add-ins. 
    Thank you for your patience and understanding. 

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