Sh4mefulIP Address: 40.107.21.75 ⚠ IP Confounder
Outbound; PTR: *.outbound.protection.outlook.com
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.
This page shows DMARC authentication failure data for this IP address. Learn more about this data.
Geolocation Information
- Country:
- AT Austria
- Region:
- Vienna
- City:
- Vienna
- Coordinates:
- 48.2049, 16.3662
WHOIS Information
- Network Name:
- MSFT
- CIDR:
40.124.0.0/16, 40.112.0.0/13, 40.120.0.0/14, 40.96.0.0/12, 40.125.0.0/17, 40.74.0.0/15, 40.76.0.0/14, 40.80.0.0/12- Owner:
- Microsoft Corporation
- Org ID:
MSFT- Address:
- One Microsoft Way, Redmond, WA 98052
- Reverse DNS:
-
mail-vi1eur05on2075.outbound.protection.outlook.com
Last updated: 2/5/2026
Analysis
This IP was first observed on May 2, 2025 and most recently on August 22, 2025. It has been associated with 2 failed authentication events affecting 2 messages, representing low but recurring activity. The IP belongs to MSFT (Microsoft Corporation), a network with activity associated with Austria. 8 other IPs in the same /24 subnet (40.107.21.*) also appear in this dataset.
Network Topology
External Reputation Lookups
Look up this IP in external threat intelligence and reputation databases (opens in new tab):
Nearby IPs
Other IPs in the 40.107.21.0/24 range observed failing DMARC:
40.107.21.40 (2 failures), 40.107.21.102 (1 failure), 40.107.21.120 (1 failure), 40.107.21.126 (1 failure), 40.107.21.45 (1 failure), 40.107.21.50 (1 failure), 40.107.21.61 (1 failure), 40.107.21.72 (1 failure)