Sh4meful DMARC Spoof Detection
IP Address: 104.47.51.171
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:
- IE Ireland
- Region:
- Leinster
- City:
- Dublin
- Coordinates:
- 53.3382, -6.2591
WHOIS Information
- Network Name:
- MSFT
- CIDR:
104.40.0.0/13- Reverse DNS:
-
mail-dbaeur03lp2171.outbound.protection.outlook.com
Last updated: 2/5/2026