Microsoft documents a mail-flow layer that detects prompt-injection content in inbound email before delivery to users or AI assistants. Detections land as High confidence phishing with technology "Prompt injection protection" (MDO Plan 2 / E5-class). Focus: instructions that try to exfiltrate via URL, reveal system prompts, or enumerate write-capable tools — including hidden/white-on-white text. Runtime Copilot safeguards remain a second layer. This is harness/context defense at the email channel, not a new CVE.