Summary
When an unexpected IP address appears in Google Postmaster Tools (GPM), it signals that something is authenticating as your domain, potentially due to misconfigured corporate mail, message forwarding without DKIM alteration, or unauthorized sending. Immediate steps involve checking DMARC reports, using header analysis to trace the IP, and examining email logs. Identify the IP's owner through hostname digging and ARIN lookups, and compare against expected IP ranges using tools like Word to the Wise SPF checker. Utilizing ActiveCampaign's DNS Verification Tool, reviewing ESP authorized sender lists, and contacting new vendors help verify legitimacy. Checking IP reputation via VirusTotal or Spamhaus is crucial. Implement proactive monitoring, limit ESP access, and add network security policies. Secure IPs with MFA, monitor domain reputation for harmful links, and investigate compromised accounts.
Key findings
- Authentication Status: Indicates something is authenticating as your domain; investigate potential causes.
- DMARC Report Review: Crucial for identifying the IP and its activities.
- IP Identification Tools: Use hostname digging and ARIN lookup for IP owner identification.
- SPF Validation: Word to the Wise's SPF checker helps compare against expected ranges.
- Authorized Sender Review: Ensure your ESP's authorized sender lists are up-to-date.
- Reputation Checking: Use VirusTotal/Spamhaus to check IP reputation for spam association.
- Header Analysis: Analyzing email headers can reveal the path an email took and the originating IP address.
Key considerations
- Proactive Monitoring Setup: Configure alerts for unusual sending patterns.
- Access Limitation: Restrict access to your Email Service Provider (ESP).
- Account Compromise Investigation: Crucial to check for and address compromised accounts.
- Security Implementation: Add network security policies and MFA to secure IPs.
- Domain Reputation Management: Monitor for harmful links to protect sender reputation.
What email marketers say
10 marketer opinions
When an unexpected IP address appears in Google Postmaster Tools, it's crucial to investigate promptly to ensure your domain's sending reputation and security. Key actions include verifying domain setup with tools like ActiveCampaign's DNS checker, analyzing email headers to trace the IP's origin, and reviewing email logs for suspicious activity. Checking the IP's reputation via services like VirusTotal or Spamhaus can quickly reveal if it's associated with spam. Additionally, review authorized sender lists within your ESP, contact new vendors to confirm IP legitimacy, and ensure DMARC records are monitored if already in place. Limiting ESP access, implementing security policies within your network, and monitoring domain reputation are also vital. Proactive measures include setting up monitoring alerts and investigating for potentially compromised accounts.
Key opinions
- Domain Verification: Use tools like ActiveCampaign's DNS Verification to ensure correct domain setup (DKIM, SPF).
- Header Analysis: Analyze email headers to trace the path and origin of the unexpected IP address.
- Log Review: Check email logs for any sending activity associated with the unfamiliar IP.
- IP Reputation: Check the IP's reputation using services like VirusTotal or Spamhaus.
- Sender Lists: Review authorized sender lists in your ESP for unauthorized additions.
- New Vendor Verification: Contact new vendors to confirm the legitimacy of their sending IPs.
- DMARC Monitoring: Monitor DMARC records to identify IPs sending from your domain.
- ESP Access Control: Limit access to your Email Service Provider to prevent unauthorized sending.
- Security Policies: Implement security policies and rules within your network to block unwanted IPs.
- Domain Reputation: Monitor domain reputation, especially for harmful links in sent emails.
Key considerations
- Proactive Monitoring: Implement proactive monitoring and alerts for changes in sending patterns.
- Compromised Accounts: Investigate for potentially compromised user accounts or systems being used for sending.
- Security Implementations: Add any relevant security measures such as multi factor authentication on your email service provider.
Marketer view
Email marketer from Sendgrid explains that it may be from a new vendor, or service. It's a good idea to contact new vendors about IP addresses to ensure they are legitimate.
1 Dec 2023 - Sendgrid
Marketer view
Email marketer from Stackoverflow recommends checking the IP reputation of the unfamiliar IP using services like VirusTotal or Spamhaus. This will quickly tell you if the IP is associated with spam or malicious activity.
21 Jan 2025 - Stackoverflow
What the experts say
6 expert opinions
When an unexpected IP address appears in Google Postmaster Tools (GPM), it indicates that something has authenticated as your domain. This can be due to corporate mail, forwarding messages without altering the DKIM signature, or potential unauthorized sending. Initial actions should include checking DMARC reports and verifying the IP address. Identifying the IP owner involves digging into the hostname and using an ARIN lookup. Utilizing tools like Word to the Wise SPF checker can help compare against your expected IP ranges. Proactive measures involve setting up monitoring alerts and investigating for compromised accounts or systems.
Key opinions
- Authentication Issue: An unexpected IP means something authenticated as your domain.
- DMARC Reports: Check DMARC reports to identify the IP address and its sending activity.
- IP Identification: Identify the IP owner by digging into the hostname and using an ARIN lookup.
- SPF Comparison: Use tools like Word to the Wise SPF checker to verify IP ranges.
- ActiveCampaign IP: The IP might be registered to ActiveCampaign, especially if using their services.
Key considerations
- Proactive Monitoring: Set up proactive monitoring and alerts to detect unexpected IPs quickly.
- Compromised Accounts: Investigate for potentially compromised user accounts or systems being used for sending.
- DKIM Signature: Someone may be forwarding emails without altering the DKIM signature.
Expert view
Expert from Spam Resource shares that it's crucial to investigate for compromised user accounts or systems. An unexpected IP could indicate a compromised account being used to send spam.
4 Nov 2021 - Spam Resource
Expert view
Expert from Email Geeks shares that you can punch your domain into <https://tools.wordtothewise.com/spf> and get a nice list of IP ranges to check against too.
14 Jan 2025 - Email Geeks
What the documentation says
5 technical articles
When an unexpected IP address appears in Google Postmaster Tools, documentation emphasizes the importance of identifying unauthorized sources to prevent spoofing. SPF records should accurately declare authorized sending IPs, and DKIM signatures can help trace the email's origin to detect potential spoofing. Implementing DMARC policies provides reporting on sending sources and allows for setting policies to reject unauthorized mail. Ensuring all IPs are secured with MFA is crucial to prevent breaches and IP-related issues.
Key findings
- Identify Unauthorized Sources: Review sending IPs in Google Postmaster Tools to identify unfamiliar sources.
- SPF Records: Ensure SPF records accurately declare all authorized sending IPs.
- DKIM Signatures: Examine DKIM signatures to trace the origin of emails and detect spoofing.
- DMARC Policies: Implement DMARC for reporting and policy setting on sending sources.
- MFA Security: Secure all IPs with MFA to prevent breaches.
Key considerations
- Prevent Spoofing: Take immediate actions to prevent potential spoofing activities.
- Email Authentication: Ensure proper implementation and maintenance of email authentication methods (SPF, DKIM, DMARC).
- Breach Prevention: Prioritize security measures like MFA to minimize the risk of security breaches.
Technical article
Documentation from Google Help explains that you should review the sending IPs listed in Google Postmaster Tools to identify any unfamiliar or unauthorized sources. This helps to spot potential spoofing or unauthorized sending from your domain.
17 Jul 2023 - Google Help
Technical article
Documentation from RFC-Editor explains that SPF records explicitly declare authorized sending IP addresses for a domain. An unexpected IP indicates a failure to properly include all sending sources in your SPF record, or potential unauthorized sending.
29 Mar 2025 - RFC-Editor.org
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