Sh4mefulIP Address: 63.251.72.195
Dormant. IP address 63.251.72.195 is registered to PF IPV4 Borrower, LLC and geolocates to United States. It was observed in sh4meful's dataset on February 14, 2025. Over the observation window, it has failed DMARC alignment once, targeting one sender domain. Its reverse DNS resolves to mta-gw-acs-002.entrustedmail.net. Network context: this address sits within UG-210 (PF IPV4 Borrower, LLC), a network sh4meful has observed producing 13 failures across 5 distinct IPs during the same window.
Failure Activity Over Time
This IP has claimed to send from 1 sender domain monitored by sh4meful. The single targeted domain suggests either a compromised sending source or a spoofing attempt focused on a specific brand.
This page shows DMARC authentication failure data for this IP address. Learn more about this data.
Geolocation Information
- Country:
- US United States
- Coordinates:
- 37.751, -97.822
WHOIS Information
- Network Name:
- UG-210
- CIDR:
63.251.84.0/23, 63.251.64.0/20, 63.251.80.0/22, 63.251.32.0/19, 63.251.16.0/20- Owner:
- PF IPV4 Borrower, LLC
- Org ID:
PIHL-4- Address:
- 1209 Orange Street, Wilmington, DE 19801
- Reverse DNS:
-
mta-gw-acs-002.entrustedmail.net
Last updated: 2/5/2026
Analysis
This IP was observed generating a single DMARC authentication failure on February 14, 2025. With only one data point, the event is better read as a single suspicious observation than a sustained campaign. Every message observed from this source failed both SPF and DKIM verification. Receiving mail providers applied a reject disposition, refusing delivery outright.
The reverse DNS record (mta-gw-acs-002.entrustedmail.net) suggests the host is configured as mail infrastructure. In the context of authentication failures, this most often indicates either a misconfigured legitimate sender or a compromised mail server being used to relay abuse.
Geolocation places the host in United States, on infrastructure operated by PF IPV4 Borrower, LLC. Abuse-reporting channels in this jurisdiction are generally responsive, and reports to the network operator can result in timely remediation.
The address is registered to PF IPV4 Borrower, LLC (UG-210), an enterprise network operator. Concentrated authentication failures on enterprise address space can indicate either a compromised internal host being used as an unauthorized sending relay, or an organization knowingly or unknowingly operating as a spam source.
Across the wider UG-210 network, 5 distinct IPs have been associated with 13 authentication failures over 13 observed messages, spanning 1 country. Most observed IPs on this network contribute to the failure count, suggesting the range as a whole warrants elevated scrutiny.
If your domain appears in the From header of mail from this address, treat it as probable spoofing. Verify that your SPF record does not authorize this host, directly or through nested include mechanisms, and that no DKIM selector you publish has been issued to it. If both checks come back clean, the receiver's reject action is doing its job.
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 PF IPV4 Borrower, LLC is listed in ARIN WHOIS records, and timely remediation is achievable through that channel.
External Reputation Lookups
Look up this IP in external threat intelligence and reputation databases (opens in new tab):
Nearby IPs
The following IP addresses share the same /24 subnet as 63.251.72.195 and have appeared in sh4meful's dataset. Related activity in nearby addresses often indicates infrastructure operated by a single actor or provider.
- 63.251.72.156 — 4 failures, first seen 10 months ago, 210 days after this address.
Recommended Action
If this IP appears in your own DMARC reports, treat it as an unauthorized sender unless you have specifically verified it as a legitimate service you use. Ensure your DMARC policy is at p=quarantine or p=reject to prevent delivery of messages this IP claims to send from your domain. If you're new to DMARC, our complete guide walks through the mechanics.