Sh4mefulIP Address: 40.74.181.208
This page shows DMARC authentication failure data for this IP address. Learn more about this data.
Geolocation Information
- Country:
- US United States
- Region:
- Texas
- City:
- San Antonio
- Coordinates:
- 29.4227, -98.4927
WHOIS Information
- Network Name:
- MSFT
- CIDR:
40.124.0.0/16, 40.80.0.0/12, 40.125.0.0/17, 40.74.0.0/15, 40.96.0.0/12, 40.76.0.0/14, 40.112.0.0/13, 40.120.0.0/14- Owner:
- Microsoft Corporation
- Org ID:
MSFT- Address:
- One Microsoft Way, Redmond, WA 98052
Analysis
This IP generated DMARC authentication failures across 4 messages between February 14, 2025 and February 26, 2025, showing low but persistent activity. Every message observed from this source failed both SPF and DKIM verification. Receiving mail providers applied a reject disposition, refusing delivery outright.
The address has no reverse DNS record. Legitimate mail infrastructure almost always publishes a PTR record, because major receivers (Gmail, Microsoft 365, Yahoo) penalize or reject mail without one, and because it is a baseline operational hygiene expectation. Its absence, combined with authentication failure, is consistent with a host being used to originate spoofed mail rather than one misconfigured by a legitimate operator.
Geolocation places the host in San Antonio, United States, on infrastructure operated by Microsoft Corporation. Abuse-reporting channels in this jurisdiction are generally responsive, and reports to the network operator can result in timely remediation.
The address is hosted on Microsoft Corporation (MSFT), a major cloud provider. Authentication failures are spread across multiple IP ranges on this network, which is consistent with the scale of a large provider's customer base.
Across the wider MSFT network, 3 distinct IPs have been associated with 4 authentication failures over 6 observed messages, spanning 2 countries. The failure pattern suggests a mix of abuse sources on this network.
If your domain appears in the From header of mail from this address, start with a misconfiguration investigation before assuming spoofing. Microsoft's infrastructure is used by many legitimate senders, and auth failures here most often reflect a broken SPF include chain, a DKIM signing gap on a shared sending path, or a forwarding rule that breaks alignment. Verify that your authorized senders on Microsoft are correctly publishing SPF and signing with DKIM before concluding the activity is malicious.
Your DMARC policy posture matters more than any IP-level response here. The enforcement action applied to this mail indicates your policy is already providing protection. Maintaining p=reject across all your domains closes the gap for attackers who manage partial alignment. Domains that remain at p=none long-term tend to be impersonated repeatedly, because the cost to the attacker of attempting is effectively zero.
Blocking this individual address has limited durability: an attacker can rotate to another address in the same /24 subnet at effectively zero cost. More durable responses include monitoring aggregate DMARC reports so new sources are visible as they emerge, tightening SPF to remove overly permissive include chains or +all mechanisms, and ensuring DKIM is signing every legitimate outbound stream so alignment failures are unambiguous. The formal abuse contact for Microsoft Corporation is listed in ARIN WHOIS records, and timely remediation is achievable through that channel.
Microsoft Network (365 vs Azure)
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.
External Reputation Lookups
Look up this IP in external threat intelligence and reputation databases (opens in new tab):