Why is my e-commerce brand seeing bad IP reputation for unknown IPs and how will it impact deliverability?
Matthew Whittaker
Co-founder & CTO, Suped
Published 17 May 2025
Updated 17 Aug 2025
8 min read
As an e-commerce brand, it can be unsettling to see bad IP reputation scores for IP addresses you don't recognize, especially when you use dedicated sending IPs. This situation can be confusing because it appears to involve traffic not directly originating from your own infrastructure. It raises critical questions about your email deliverability and overall brand perception, particularly for a business that relies heavily on email communication for sales and customer engagement.
Understanding why these unknown IPs are showing up in your dashboard and what impact they might have on your deliverability is crucial. While your own dedicated IPs might have a pristine reputation, these external factors can still influence how inbox providers view your domain.
Understanding unknown IP reputation
The appearance of unknown IPs with poor reputations in your dashboard usually points to one of two scenarios. First, it could be a case of domain spoofing, where malicious actors are forging your domain in the From: address to send spam. These emails are originating from their IPs, but because they appear to come from your domain, the associated IP reputation is mistakenly linked to your brand in some reputation monitoring systems. Second, it could relate to how certain email service providers (ESPs) handle shared IP pools, even if you’re primarily on a dedicated IP, or services that aren't fully configured to authenticate properly, leading to unaligned traffic.
Some reputation monitoring dashboards aggregate all IP addresses seen sending mail for your domain, regardless of whether that mail was properly authenticated or if it was legitimate. This comprehensive view can inadvertently highlight rogue or unauthenticated traffic that is attempting to impersonate your domain. It’s important to understand this distinction, as not all reported bad IP reputation directly reflects issues with your authorized sending infrastructure.
Identifying unknown IPs
These are IP addresses that are sending emails claiming to be from your domain but are not part of your designated sending infrastructure. They often stem from unauthorized senders, compromised accounts, or misconfigured third-party services.
Impact on your brand
While your legitimate emails might still have good deliverability, the existence of these unknown, poorly reputed IPs can create a shadow reputation. This can potentially lead to some inbox providers (ISPs) flagging your domain with increased scrutiny, especially if they heavily weigh IP reputation for domains with high traffic volumes, like e-commerce brands.
The role of authentication
Authentication protocols such as SPF, DKIM, and DMARC are your primary defense against unauthorized sending. When an unknown IP sends mail purportedly from your domain, these protocols are designed to detect if the email is legitimate. If the email fails these checks, particularly DMARC, it tells receiving mail servers that the email is not authorized. However, if your DMARC policy is set to p=none, these unauthorized emails may still reach inboxes, influencing your reputation negatively. You can learn more about DMARC tags and their meanings.
DMARC reports are invaluable here, as they provide detailed insights into who is sending emails using your domain and whether those emails pass or fail authentication. By analyzing these reports, you can identify the source of the unknown IPs. Even if the emails fail authentication, the mere attempt to send using your domain might still contribute to a perceived bad IP reputation in certain monitoring systems. Checking these reports can help you understand the scale of the problem and if malicious activity is present. If you need a more in-depth look, consider this guide on IP reputation from Mailchimp.
IP reputation
This primarily refers to the trustworthiness of the specific server (IP address) sending the email. If the IP is associated with spam, phishing, or other abusive sending patterns, it will develop a poor reputation. Unknown IPs with bad reputations will appear if they are forging your domain in some way.
Domain reputation
This reflects the overall trustworthiness of your domain as an email sender. It's built on factors like consistent authentication, low spam complaints, high engagement, and minimal bounces. While distinct from IP reputation, a good domain reputation can sometimes mitigate the impact of rogue IPs, especially if your DMARC policy is robust. However, a significant number of unauthenticated emails can still degrade your domain reputation.
Impact on deliverability
While your domain reputation might appear normal if your authorized sending is strong, bad IP reputation associated with unknown IPs can still indirectly impact your deliverability. ISPs use a complex web of signals to determine inbox placement. If they see a significant volume of unauthenticated (or poorly authenticated) mail appearing to originate from your domain, even if it's from unknown IPs, it can trigger alarms. This leads to higher spam filtering rates or even outright rejections, affecting your legitimate transactional and marketing emails.
For an e-commerce brand, this impact can be particularly damaging. Reduced inbox placement means fewer customers receiving critical order confirmations, shipping updates, or promotional offers. This directly translates to lost sales, decreased customer satisfaction, and a damaged brand image. Your carefully crafted email campaigns might never reach their intended audience, diminishing your marketing ROI.
The tricky part is that if these emails aren't successfully authenticating against your SPF or DKIM records, then technically, the domain reputation should remain largely unaffected. However, the presence of your domain in the From: header or return-path on mail originating from these bad IPs can still cause ISPs to take notice. Think of it like this: even if someone is driving a stolen car with your license plate, the police will still look for your car. ISPs use IP reputation as a significant factor in their filtering decisions.
Mitigating the risks
The first step is to dive deep into your DMARC reports. These reports will explicitly tell you which IPs are sending mail for your domain and whether they are passing SPF or DKIM alignment. Look for sources that are failing DMARC and are not your known sending IPs. This is often the smoking gun for unauthorized sending. You can leverage a DMARC monitoring solution to get actionable insights from these XML reports.
Next, review your SPF record. An overly permissive SPF record, or one that exceeds the 10 DNS lookup limit (as defined in RFC 7208 section 4.6.4), can be a vulnerability. Ensure it only includes legitimate sending sources and is as concise as possible. If you suspect an SPF DNS timeout or similar issues, address them promptly. Remove any unused or outdated includes. A tight SPF record makes it harder for unauthorized parties to leverage your domain.
Example SPF record: This is a basic example. Your record will be specific to your sending services.
If DMARC reports confirm spoofing, consider moving your DMARC policy from p=none to p=quarantine or even p=reject. This instructs receiving servers to either quarantine (send to spam) or reject unauthenticated emails, significantly reducing the impact of spoofing. Regularly monitor Google Postmaster Tools (if applicable to your audience) to track your domain's reputation directly with Google.
Finally, ensure all your legitimate sending services, including transactional and marketing email platforms, are properly authenticated. Confirm your DKIM records are correctly set up for all subdomains and domains used for sending. A unified and strong authentication posture will help ISPs differentiate your legitimate traffic from unauthorized attempts, helping to clean up any bad IP or domain reputation being attributed to your brand.
Maintaining your brand's email integrity
Seeing bad IP reputation for unknown IPs can be a signal that something is amiss with your domain's email ecosystem. While it might not always directly impact your primary deliverability if your core sending practices are solid, it's a symptom that warrants investigation. By leveraging DMARC reports, tightening SPF, and ensuring consistent authentication across all sending sources, you can effectively mitigate the risks posed by these unknown IPs and maintain a robust email deliverability for your e-commerce brand.
Staying proactive with your email security and deliverability measures will protect your brand's reputation and ensure your crucial emails reach your customers. Addressing these issues can greatly improve your email IP and domain reputation, boosting overall inbox placement.
Views from the trenches
Best practices
Actively monitor your DMARC reports for unauthenticated traffic that appears to be forging your domain.
Ensure your SPF record is meticulously configured to only include authorized sending IPs and services, without exceeding the 10-lookup limit.
Implement a DMARC policy of quarantine or reject after a period of monitoring to instruct ISPs on how to handle unauthenticated mail.
Maintain consistent and correct DKIM signatures across all legitimate email sending platforms.
Regularly check Google Postmaster Tools for insights into your domain and IP reputation from Google's perspective.
Common pitfalls
Ignoring bad IP reputation for unknown IPs, assuming it won't impact your deliverability because your core IPs are good.
Having an overly broad SPF record that allows unauthorized senders to pass SPF checks.
Not having DMARC implemented, or having a p=none policy indefinitely, allowing spoofed emails to reach inboxes.
Failing to track your domain's sending activity outside of your primary ESP, leading to blind spots.
Underestimating the cumulative effect of low-volume, unauthenticated mail on overall sender trust.
Expert tips
DMARC reports are a goldmine for identifying unauthorized sending; analyze them regularly for IPs not belonging to your infrastructure.
Even if your core sending IPs have a good reputation, unauthenticated spoofing can create a 'shadow reputation' that ISPs may notice.
A tight SPF record and a DMARC policy enforced at quarantine or reject are your best defense against domain abuse and reputation decay.
Google Postmaster Tools can provide specific insights into how Google views your IP and domain reputation, which is crucial for deliverability.
Small, consistent efforts in email authentication and monitoring yield significant long-term benefits for inbox placement.
Marketer view
A marketer from Email Geeks says that the bad reputation seen on the dashboard is likely caused by bad actors on those specific IP addresses.
2024-08-08 - Email Geeks
Expert view
An expert from Email Geeks suggests that someone might be using the domain in their return path or forging the domain to send spam. Cleaning up the SPF record will help confirm if this is the cause.
