Sh4meful DMARC Spoof Detection
IP Address: 104.47.73.40
Differentiating between Office 365, including email protection services, and Azure (public cloud) when diagnosing incidents is challenging because they utilize shared Microsoft-owned IP ranges. Most of this is probably O365/Outlook or Defender protection breaking DKIM and SPF authentication. Disambiguation is a work-in-progress.
About this Data
▶The data here is from DMARC analysis for domains I administer, drawn from a larger dataset (comprising millions of authentication records and messages). These entries are from email attempts that failed both SPF and DKIM (and there are often alignment issues - hidden here). In many cases, these failures indicate unauthorized use of the domain name, and are commonly associated with spoofing, phishing, or other abusive mail activity.
Geolocation Information
- Country:
- US United States
- Region:
- Iowa
- City:
- Des Moines
- Coordinates:
- 41.6015, -93.6127
WHOIS Information
- Network Name:
- MSFT
- CIDR:
104.40.0.0/13- Reverse DNS:
-
mail-dm6nam04lp2040.outbound.protection.outlook.com
Last updated: 2/5/2026
Failures Detected from this IP
Showing 1-25 of 25 (failures, affecting 28 messages)| Date ▼ | Messages |
|---|---|
| 9/4/2025 | 1 |
| 7/17/2025 | 1 |
| 7/11/2025 | 1 |
| 7/3/2025 | 1 |
| 6/27/2025 | 2 |
| 6/26/2025 | 1 |
| 6/12/2025 | 1 |
| 6/6/2025 | 1 |
| 4/30/2025 | 1 |
| 2/28/2025 | 1 |
| 2/26/2025 | 1 |
| 2/14/2025 | 1 |
| 1/17/2025 | 1 |
| 12/20/2024 | 1 |
| 12/19/2024 | 1 |
| 12/11/2024 | 1 |
| 11/13/2024 | 1 |
| 11/12/2024 | 1 |
| 10/30/2024 | 1 |
| 10/23/2024 | 1 |
| 9/27/2024 | 1 |
| 9/18/2024 | 1 |
| 5/31/2024 | 1 |
| 4/17/2024 | 2 |
| 3/13/2024 | 2 |