DMARC Spoof Detection, United Kingdom
Clear Clear FilterThis page shows DMARC authentication failures originating from United Kingdom. Learn more about this data.
United Kingdom accounts for 286 DMARC authentication failures observed by sh4meful over the observation window, sourced from 87 distinct IP addresses across 33 networks. This represents approximately 0.4% of total failure volume observed. Activity from United Kingdom has increased over the last 30 days compared with the prior 30-day period. The most active source is Amazon with 63 failures across 1 IP address.
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Top Networks in United Kingdom
Ten most active networks sourcing DMARC failures from United Kingdom:
| Network | Organization | Failures | Distinct IPs | Top City |
|---|---|---|---|---|
| AT-88-Z | Amazon | 63 | 1 | City of London |
| MIMECAST-NET2 | Mimecast | 28 | 1 | — |
| MIMECAST-NET | Mimecast | 27 | 2 | — |
| MSFT | Microsoft | 35 | 27 | London |
| UK-MICROSOFT-20060601 | Microsoft | 30 | 10 | London |
| UK-PROOFPOINT-20151223 | Proofpoint | 23 | 3 | — |
| MERULA | — | 8 | 1 | Cambridge |
| UK-MIMECAST-NET3 | — | 8 | 3 | — |
| HEL-MHD | — | 9 | 2 | — |
| UK-MISTRAL-970924 | — | 8 | 4 | — |
Amazon and Mimecast together account for 36% of failure volume from this country. Distribution across many networks is consistent with commodity spoofing infrastructure operating from this geography.
Failure Activity Over Time
Peak activity was observed in the week of July 6, 2026 with 4 failures recorded. Activity in the most recent 30-day window increased sharply compared with the prior period (7 vs 1 failures).
Regional Context
Compared with peer geographies in Northern Europe, United Kingdom's failure volume is above the regional median. Countries in this region collectively contributed 4% of failures observed.
Failures
Showing 91-100 of 286 failures, affecting 393 messages| Date ▼ | Source IP | Country | City | Network | Messages |
|---|---|---|---|---|---|
| 9/26/2025 | GB United Kingdom | 4 | |||
| 9/26/2025 | GB United Kingdom | 2 | |||
| 9/25/2025 | GB United Kingdom | London | 1 | ||
| 9/24/2025 | GB United Kingdom | Cardiff | 1 | ||
| 9/24/2025 | GB United Kingdom | Cardiff | 1 | ||
| 9/24/2025 | GB United Kingdom | City of London | 1 | ||
| 9/24/2025 | GB United Kingdom | City of London | 2 | ||
| 9/24/2025 | GB United Kingdom | City of London | 1 | ||
| 9/23/2025 | GB United Kingdom | London | 1 | ||
| 9/17/2025 | GB United Kingdom | City of London | 2 |
What This Means
Country-level patterns don't imply that mail from United Kingdom 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.