DMARC Spoof Detection, Japan
Clear Clear FilterThis page shows DMARC authentication failures originating from Japan. Learn more about this data.
Japan accounts for 252 DMARC authentication failures observed by sh4meful over the observation window, sourced from 76 distinct IP addresses across 15 networks. This represents approximately 0.3% of total failure volume observed. Activity from Japan has declined over the last 30 days compared with the prior 30-day period. The most active source is Microsoft with 144 failures across 21 IP addresses.
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Top Networks in Japan
Ten most active networks sourcing DMARC failures from Japan:
| Network | Organization | Failures | Distinct IPs | Top City |
|---|---|---|---|---|
| UK-MICROSOFT-20060601 | Microsoft | 144 | 21 | Osaka |
| MSFT | Microsoft | 66 | 37 | Tokyo |
| KIR | — | 10 | 2 | — |
| SAKURA-NET | — | 12 | 3 | Hiyoshi |
| RIPE-ERX-147-44-0-0 | — | 5 | 3 | Tokyo |
| DIX-CL | — | 5 | 1 | — |
| ASAHI-NET | — | 2 | 1 | Tokorozawa |
| CSF-NET-CIDR-BLK-JP | — | 1 | 1 | — |
| NIAC | — | 1 | 1 | Nagoya |
| OCN | — | 1 | 1 | — |
Microsoft and Microsoft together account for 85% of failure volume from this country. Concentration in a small number of networks suggests targeted infrastructure rather than diffuse compromise.
Failure Activity Over Time
Peak activity was observed in the week of June 22, 2026 with 3 failures recorded. Activity in the most recent 30-day window declined sharply compared with the prior period (0 vs 3 failures).
Regional Context
Compared with peer geographies in Eastern Asia, Japan's failure volume is above the regional median. Countries in this region collectively contributed 1% of failures observed.
Failures
Showing 1-10 of 252 failures, affecting 331 messagesWhat This Means
Country-level patterns don't imply that mail from Japan is inherently malicious. Many failures reflect misconfigured legitimate senders, forwarded messages that break authentication, or automated infrastructure operating without authorization. Domain owners investigating a specific failure should look at the source IP and network details rather than the country alone. Our DMARC guide explains how to interpret these signals in your own reports.