Microsoft has released detailed performance figures for its email security product, giving businesses a clearer picture of how well their inboxes are protected against malicious messages.
The data, drawn from telemetry collected between November 2025 and January 2026, covers how Microsoft Defender for Office 365 detected and removed threats both before and after they reached users' inboxes.
When a malicious email slips past initial filters and lands in an inbox, a feature called zero-hour auto purge automatically hunts it down and removes it.
Microsoft says that mechanism handled 70.8% of post-delivery threat removal on average during the period, with the remaining 29.2% attributed to third-party integrated cloud email security (ICES) vendors, which plug into Defender to add an extra layer of detection.
The company also measured how often threats escaped detection entirely, classifying a threat as "missed" if it bypassed pre-delivery filters and was not quickly removed afterward.
By that measure, Microsoft said Defender missed fewer high-severity threats than other solutions included in the evaluation.
The ICES partner ecosystem now includes four vendors, and Microsoft says the integrations are designed so that security teams manage everything through a single interface rather than juggling multiple consoles.
Jeff Pinkston, vice president and general manager of Microsoft Defender for Office 365, was direct about the intent behind publishing the numbers.
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"This isn't about claiming perfection," Pinkston said in the blog post. "It's about showing the work, sharing the numbers, and giving customers the information they need to make informed security decisions."
Microsoft said it plans to publish updated benchmarking figures regularly, and has directed customers to its benchmarking site for full methodology details.
The recap
- Microsoft published Defender for Office 365 benchmarking results.
- Defender removed 70.8% of inbox-delivered threats post-delivery on average.
- Microsoft will publish updated benchmarking insights on a regular basis.