# SparkPost: We are observing an elevated rate of spam foldering and open rates for messages destined to Office 365 domains

- Impact (vendor’s label): none
- Status: resolved
- Started: 2024-02-06 17:56 UTC · Resolved: 2024-02-07 22:03 UTC · Duration: 28 h
- Updates: 1
- [Vendor status page: https://status.sparkpost.com/incidents/8fn1mphdk7hp](https://status.sparkpost.com/incidents/8fn1mphdk7hp)
- [Company: SparkPost](https://rewindex.com/company/sparkpost.md)

## Timeline of updates

- **resolved** 2024-02-07 22:03 UTC: This incident has been resolved. Summary: Beginning last week we made a change to add a URL to the list-unsubscribe header to be compliant with new rule “one-click” unsubscribe requirements from Gmail and Yahoo. After this update, some customers started reporting an increase in \[new\] junk foldering of messages destined to Office 365 addresses - it appears they were flagged by Microsoft’s Defender filtering framework. We worked with Microsoft who made changes to address this issue. In addition, some customers reported a large increase in opens and clicks on Monday and Tuesday of this week that we believe were caused by some action by Microsoft - likely a reclassification or redelivery routine.

_From the vendor’s published history: only the final update text is available for incidents before Rewindex began polling this page._


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Canonical: https://rewindex.com/company/sparkpost/incidents/8fn1mphdk7hp · Markdown: https://rewindex.com/company/sparkpost/incidents/8fn1mphdk7hp.md · JSON: https://rewindex.com/api/v1/companies/sparkpost/incidents/8fn1mphdk7hp · Generated 2026-10-19T22:28:16.985Z