Sh4meful DMARC Spoof Detection
IP Address: 2a01:111:f403:c10c::1
According to reverse-DNS, this is a host domain utilized by Microsoft 365 (formerly Office 365) to manage and secure outbound email traffic. It acts as a mail transfer agent (MTA) that filters outgoing messages to prevent spam and malicious content. Format: .outbound.protection.outlook.com. However, we've seen actual spoof attempts and SPAM from MS infrastructure so not classing this a confounder.
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:
- Texas
- City:
- San Antonio
- Coordinates:
- 29.4227, -98.4927
WHOIS Information
- Network Name:
- UK-MICROSOFT-20060601
- Owner:
- ORG-MA42-RIPE
- Reverse DNS:
-
mail-southcentralusazlp170130001.outbound.protection.outlook.com
Last updated: 2/5/2026