AI Security
DKIM Replay Attacks: Six Email DNS Settings Domain Owners Should Review Now
Phishing emails carrying an official-account mark made headlines in Japan. Even when SPF, DKIM and DMARC all pass, spoofing is not over. This article separates what NTT Docomo and Rakuten Card have disclosed from what engineers have analyzed, explains how a DKIM replay attack works, and lists six DNS and mail-delivery settings for domain owners, based on the RFCs and M3AAWG guidance.
2026-10-19Ryuta Hamamoto