Clarity in complexity: New insights for transparent email security

Microsoft’s second email security benchmarking report compares Defender-only, SEG+Defender, and ICES+Defender deployments using real-world threats, with an updated methodology that corrects misattribution from journaling/reinjection and includes Defender’s zero-hour auto purge. Findings show ICES layers notably reduce marketing/bulk email (~9.4% improvement) with modest gains for spam (~1.65%) and malicious (~0.5%) filtering; post-delivery, Defender removed ~45% of malicious emails that reached inboxes while ICES vendors accounted for ~55%. SEG comparisons indicate Defender missed fewer threats overall. The report underscores transparency and quarterly updates to guide optimization of layered email security.