We’re deprecating the previewImageUrl property in the resourceVisualization complex type for Insights items where the referenced resource is a file attachment (resourceReference.type = fileAttachment). This affects responses from the Insights List shared and Insights List used APIs when the underlying resource is an email attachment.
What’s changing and why
The previewImageUrl property is no longer returned for file attachment items. File attachments don’t have a consistent preview experience across Microsoft 365, so removing this property simplifies the API and aligns it with supported preview scenarios. Items that reference cloud files (like driveItem) aren’t impacted.
Timeline
- Deprecation notice: Effective immediately
- Removal date: November 1, 2027
Action required
- If your app uses
resourceVisualization.previewImageUrlfor file attachment insights, update your logic to handle the absence of this property. - For previews, prefer modern attachments (cloud files) and use the driveItem: preview action where applicable.
Appreciate the transparency around this change. The deprecation seems like a good step toward unifying preview behavior across Microsoft 365 resources. It would be helpful if future documentation included migration examples showing how to transition from using:
into leveraging
for modern attachments, that would make adoption even smoother for API consumers.