Why is Google Postmaster Tools reporting IPs not associated with my domain?

Marketer from Email Geeks suggests that if Google has reported the IPs in GPT but has not sent DMARC reports, there might be issues with the DMARC setup, possibly involving spoofed sub-domains not covered by the DMARC record.

Email marketer from EmailDeliverabilityBlog.com explains that continuously monitoring your domain and IP reputation using tools like Google Postmaster Tools is crucial. Regularly check for any unusual IP activity and investigate any discrepancies promptly to maintain a healthy sender reputation.

Email marketer from EmailVendorSelection.com responds that shared IP addresses used by multiple senders can lead to reputation issues. If other users on the shared IP engage in spammy behavior, it can affect your sending reputation and cause Google Postmaster Tools to flag the IP even if your own sending practices are legitimate.

Email marketer from Reddit user explains that if you have a DMARC policy set to 'none', you're essentially monitoring email abuse, not preventing it. Google may report IPs sending unauthorized emails from your domain, but the emails will still be delivered. A stricter DMARC policy (quarantine or reject) helps prevent this.

Email marketer from Mailjet shares that seeing unauthorized IP addresses in Google Postmaster Tools can indicate domain spoofing, where someone is sending emails using your domain without your permission. This can harm your sender reputation and lead to deliverability issues.

Email marketer from StackExchange suggests that someone might be spoofing subdomains of your primary domain. Even if your main domain is properly authenticated, rogue emails from unauthenticated subdomains can still harm your overall reputation and show up in Google Postmaster Tools reports.

Email marketer from SendGrid shares that implementing strict email security best practices, including SPF, DKIM, and DMARC, is essential to protect your domain from unauthorized use. Regularly review your authentication settings and DMARC reports to identify and address potential issues.

Email marketer from EmailGeeks Forum explains that one potential reason for unexpected IPs in Postmaster Tools is an authentication problem stemming from forwarded emails. Sometimes, forwarding can break SPF or DKIM, causing the email to appear as if it's coming from an unauthorized source.

Email marketer from SparkPost suggests that discrepancies in reported IPs can stem from shared infrastructure or cloud services, where multiple entities might use the same IPs. If one of these entities engages in poor sending practices, it can negatively impact the reputation of the shared IPs, affecting your deliverability.

Email marketer from WebHostingTalk shares that in shared hosting environments, your website might be on the same IP as other sites. If one of those sites sends spam, it could affect the IP's reputation, leading to Google Postmaster Tools reporting it as having a bad reputation, even though you're not directly responsible.

Expert from Email Geeks shares that four of the listed IP addresses are Linode boxes and one is OVH, both of which are bottom-end VPS providers known for issues with bad actors.

Expert from Word to the Wise explains that implementing and actively monitoring DMARC reports is essential. These reports highlight which IPs are sending emails using your domain, allowing you to identify and address any unauthorized sending sources that might be causing Google Postmaster Tools to flag unexpected IPs.

Expert from Spam Resource explains that unexpected IPs showing in Postmaster Tools often indicate that someone else is using your domain to send email. Thoroughly investigate your SPF records, DMARC reports, and DKIM signatures to identify and stop the unauthorized sending sources.

Expert from Email Geeks explains that GPT can be overly inclusive when listing sending IPs, possibly including those forging the domain in the 5321.from or forwarding emails while maintaining the DKIM signature. She advises not spending too much time diagnosing issues with IPs that don't belong to the user, especially if the domain reputation remains high.

Documentation from RFC Editor specifies that Sender Policy Framework (SPF) records should accurately list all authorized sending sources for your domain. If there are discrepancies between your SPF record and the IPs sending mail claiming to be from your domain, Google Postmaster Tools may flag these IPs.

Documentation from Google Support explains that Google Postmaster Tools might report IPs not directly associated with your sending domain if those IPs are involved in sending mail that impersonates your domain or if there are authentication issues where your domain is being used without proper authorization.

Documentation from DMARC.org explains the importance of a properly configured DMARC policy to instruct recipient mail servers on how to handle emails that fail SPF and DKIM checks. Without a robust DMARC policy, unauthorized use of your domain can continue, leading to issues reported in Google Postmaster Tools.

Documentation from Microsoft explains that DomainKeys Identified Mail (DKIM) signatures should be correctly implemented to authenticate your outgoing emails. If DKIM signatures are missing or invalid, emails might be flagged, and associated IPs may appear suspicious in Google Postmaster Tools.