IP Address: 205.220.183.129 ⚠ Network Confounder

⚠ Network Confounder Detected: Proofpoint Email Security
Proofpoint network identifier

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:: PROOF
CIDR:: 205.220.160.0/19
Owner:: Proofpoint, Inc.
Org ID:: PROOF
Address:: 925 W Maude Ave, Sunnyvale, CA 94085
Reverse DNS:: mx0b-0077b901.pphosted.com
Last updated: 2/5/2026

Analysis

This IP was first observed on February 14, 2025 and most recently on December 3, 2025. It has been associated with 9 failed authentication events affecting 16 messages, representing moderate activity. The IP belongs to PROOF (Proofpoint, Inc.), a network with activity associated with United States. One other IP in the same /24 subnet (205.220.183.*) also appears in this dataset.

Failures Detected from this IP

Showing 1-9 of 9 failures, affecting 16 messages

Date ▼	Messages
12/3/2025	1
9/24/2025	1
9/17/2025	3
9/10/2025	2
8/1/2025	1
7/23/2025	2
7/17/2025	2
7/11/2025	3
2/14/2025	1

External Reputation Lookups

Look up this IP in external threat intelligence and reputation databases (opens in new tab):

AbuseIPDB Cisco Talos Project Honey Pot GreyNoise VirusTotal Shodan Censys Spamhaus

Nearby IPs

Other IPs in the 205.220.183.0/24 range observed failing DMARC:

205.220.183.242 (3 failures)