Issue Publishing Outlook Extension using Latest Agent Toolkit with Unified Manifest

Question

Hello,

We are trying to publish an outlook extension that uses the latest Agent Toolkit. We posted the issue on the official O365 Stackoverflow page:

https://stackoverflow.com/questions/79952604/outlook-add-in-generated-with-microsoft-365-agents-toolkit-unclear-production

However, we got no response.

Appreciate any help.

Thanks

Answer 1

Hi @Fleet 56

Based on the information you provided, I have reviewed your question on Stack Overflow and researched some additional details regarding your issue.

From the manifest information you shared, the main point I want to highlight is that your package is currently using the devPreview version of the Teams/Microsoft 365 manifest schema. The Agents Toolkit generates this devPreview schema to make local testing and experimental features convenient during development. However, because it is built for preview purposes, it will likely not be accepted as-is by the production validation pipelines in the Microsoft 365 Developer Portal or the M365 Admin Center, which apply much stricter validation rules.

Regarding Office Add-ins, according to Microsoft Learn documentation, there are two types of manifests available:

• Add-in Only Manifest (XML): The legacy format that fully supports production deployment for Outlook and other traditional Office add-ins.
• Unified Manifest for Microsoft 365 (JSON): The newer format that allows you to combine your add-in with other Microsoft 365 extensions inside a single app package.

In this case, you should treat the output from the toolkit as a development scaffold. Before publishing your app, you will need to align it with the standard unified manifest format and ensure it uses a GA (Generally Available) schema version currently supported by the production portals.

So, in short:

• The Toolkit-generated devPreview manifest may be valid for local development/testing, but it should not be assumed to be publishable as-is.
• Move to a released manifest schema version.
• Upload the unified manifest package as a Microsoft 365/Teams app package, not as a legacy Office XML add-in.
• Ensure extensions.requirements.scopes includes mail.
• Validate the ZIP package, icon dimensions/transparency, HTTPS URLs, validDomains, and developer metadata before submitting.

For more details on how to structure this correctly, please refer to the following official documentation:

Office Add-ins with the unified app manifest for Microsoft 365.

I hope this information help.

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