SSO fallback for Outlook add-in required for what cases?

Kaczmarek, Dan 0 Reputation points
2024-12-13T14:59:08.0633333+00:00

I'm developing an addin that uses msal-browser to implement SSO in a similar way to https://github.com/OfficeDev/Office-Add-in-samples/blob/main/Samples/auth/Outlook-Add-in-SSO-NAA-IE/README.md (though using a standard public client application instead of a nested one due to NAA specific issues tracked elsewhere).

My question is what are the potential cases for currently supported Outlook versions where this form of SSO is unavailable? I know that some versions of Outlook that use Trident/IE based webviews would have issues which would require a fallback like in that sample, but given that all of those Outlook versions seem to leave support by Oct 2025 we're fine with that given our timelines. Are there any other cases where SSO might not be supported that we should concern ourselves with?

Office Development
Office Development
Office: A suite of Microsoft productivity software that supports common business tasks, including word processing, email, presentations, and data management and analysis.Development: The process of researching, productizing, and refining new or existing technologies.
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  1. David Chesnut 166 Reputation points Microsoft Employee
    2024-12-13T19:50:09.67+00:00

    Hi Dan, The general availability status for NAA is documented here: https://zcusa.951200.xyz/en-us/javascript/api/requirement-sets/common/nested-app-auth-requirement-sets. We'll update that as NAA is GA on more platforms.

    When NAA is not available, msal-browser will automatically fall back to using a public client application and use a dialog to sign in the user. However on some older Outlook clients there is a bug that causes an "about" error to show to the user. There's a fallback workaround for this in the sample https://github.com/OfficeDev/Office-Add-in-samples/tree/main/Samples/auth/Outlook-Add-in-SSO-NAA

    Details are in the readme about fallback.

    And for a list of which older platforms used the trident (IE11) webview, see https://zcusa.951200.xyz/en-us/office/dev/add-ins/concepts/browsers-used-by-office-web-add-ins

    Cheers,

    David


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