Sh4mefulIP Address: 74.234.83.58
Newly observed. IP address 74.234.83.58 is registered to Microsoft Corporation and geolocates to Dublin, Ireland. It was observed in sh4meful's dataset on September 20, 2026. Over the observation window, it has failed DMARC alignment once, targeting one sender domain. It has no reverse DNS record. Network context: this address sits within MSFT (Microsoft Corporation), a network sh4meful has observed producing 7 failures across 6 distinct IPs during the same window.
Failure Activity Over Time
Peak activity was observed in the week of September 14, 2026 with 1 failures recorded. Activity in the most recent 30-day window increased sharply compared with the prior period (1 vs 0 failures).
This IP has claimed to send from 1 sender domain monitored by sh4meful. Because this address belongs to Microsoft's shared mail infrastructure, multiple claimed sender domains most likely reflect legitimate multi-tenant sending rather than a bulk spoofing operation.
This page shows DMARC authentication failure data for this IP address. Learn more about this data.
Geolocation Information
- Country:
- IE Ireland
- Region:
- Leinster
- City:
- Dublin
- Coordinates:
- 53.3382, -6.2591
WHOIS Information
- Network Name:
- MSFT
- CIDR:
74.234.0.0/15- Owner:
- Microsoft Corporation
- Org ID:
MSFT- Address:
- One Microsoft Way, Redmond, WA 98052
Analysis
This IP was observed generating a single DMARC authentication failure on September 20, 2026. 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 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 Dublin, Ireland, 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). While major cloud platforms carry large volumes of legitimate mail, concentrations of authentication failures on specific ranges often indicate either a compromised customer account or a pattern of abuse-tolerant customer behavior within that range.
Across the wider MSFT network, 6 distinct IPs have been associated with 7 authentication failures over 9 observed messages, spanning 4 countries. 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, 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/RIPE/APNIC 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):
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.