What should I do if my website is on a Fastly IP range listed on Spamhaus but I don't send email from that IP?
Matthew Whittaker
Co-founder & CTO, Suped
Published 6 Jul 2025
Updated 16 Aug 2025
7 min read
It can be alarming to discover that an IP address associated with your website, especially one managed by a CDN provider like Fastly, is listed on a major email blocklist (also known as a blacklist) like Spamhaus. Your immediate concern might be about your email deliverability, even if you are certain your website doesn't send emails directly.
The key here is understanding the distinction between an IP address used for web hosting and one used for email sending. While related to your online presence, these two functions typically operate on entirely separate infrastructures, especially when using a CDN and a dedicated email service.
I'll guide you through why this happens, how to assess the actual impact, and what steps you should take to protect your email deliverability and overall online reputation.
Spamhaus and other blocklists (blacklists) track IPs for various malicious activities, not just sending spam emails. This can include hosting malware, phishing sites, or acting as command and control servers for botnets. When you use a CDN like Fastly or a platform like GitHub Pages, your website shares IP addresses with many other users. This is a common practice to optimize performance and reduce costs.
If even one of those other users on the shared IP range engages in malicious behavior, the entire IP range, or a specific subnet, may be listed by a blocklist. This is a measure to prevent the spread of threats across the internet, even if your specific website is entirely legitimate and secure. It's often a broad blocklist (or blacklist) of an entire network range, not a specific indictment of your site's activity.
The key takeaway is that such a listing isn't necessarily targeting your email sending practices. Instead, it’s often about the reputation of the shared infrastructure for web hosting. The primary impact, if any, would be on web traffic to sites hosted on that IP range, not on email directly.
Why CDN IPs get listed
CDNs like Fastly provide infrastructure to many websites. When one site on a shared IP range hosts malware, phishing, or other abusive content, the entire IP range or subnet might be added to a blocklist (blacklist) by organizations like Spamhaus. This protects recipients from various online threats, even if the primary issue isn't email spam directly originating from your specific website.
Diagnosing the listing and its true impact
The first step is to check the specific Spamhaus listing for your Fastly IP. The listing will provide details on why the IP was added, such as if it's part of an SBL (Spamhaus Block List) or XBL (Exploits Block List) entry. If the listing states it's for a network range (e.g., a /24 subnet), this strongly indicates a shared infrastructure issue rather than a specific problem with your website's actions.
Crucially, you need to verify if any email bounces you are experiencing are indeed linked to this Fastly IP listing. Your helpdesk software might be reporting hard bounces, but the bounce message usually includes the IP address that caused the rejection. Compare that IP to your Fastly IP. In most cases, if your website is purely static and not configured to send emails, the bounce IP will belong to your actual email service provider (ESP) or mail server, which is distinct from your Fastly IP.
Understanding how various email blocklists (or blacklists) function is vital. Not all blocklists are the same, and their purpose dictates what kind of traffic they impact. While Spamhaus provides various blocklists, some are specifically for email sending IPs, while others target IPs known for hosting malicious content, regardless of email activity. For more on the specifics, Spamhaus offers a useful FAQ on DNSBL usage.
Feature
Website IP blocklist context
Email IP blocklist context
Purpose
To prevent access to malicious websites or content.
To prevent spam and malicious emails from reaching inboxes.
Common providers
Firewalls, security tools, some DNSBLs (like Spamhaus for hosting).
Spamhaus, Barracuda, Proofpoint, various RBLs (real-time blockhole lists).
Impact on your services
May block users from accessing your website, affects web traffic.
May cause your emails to be rejected or routed to spam folders.
Contact the hosting provider or CDN, move services, report false positives.
Investigate email sending practices, delist from blocklists (blacklists), improve authentication.
Impact on your website versus email deliverability
If your website is not sending emails and the Fastly IP listing is indeed a network-wide block (blacklist) due to other users, it is unlikely to directly impact your email deliverability. This is because your actual email sending is handled by a separate mail server or Email Service Provider (ESP), using different IP addresses. Mail servers check the reputation of the sender's IP, which, in your case, is not the Fastly IP.
The main concern for you would be if the blocklist (blacklist) also affects web traffic, meaning some users might be unable to access your website. While email blocklists primarily affect email, a severe enough listing of an IP range could lead to some firewalls or security software blocking access to websites hosted on those IPs. However, for a CDN IP, this is generally less common than for dedicated email sending IPs.
Therefore, your focus should remain on maintaining a strong email sender reputation for your domain and ensuring your email sending infrastructure is clean and compliant. This specific Fastly IP listing is more of an infrastructure issue for Fastly to resolve with Spamhaus, rather than something you can directly control or that typically impacts your email sending.
Website hosting concerns
Your primary concern should be that your website, or other sites on the shared IP range, aren't actively engaging in malicious behavior. If your own site is compromised, address that immediately. If it's a shared network issue, your web host (Fastly) needs to address it with the blocklist (blacklist) operator.
Email deliverability assurance
Ensure your email sending practices are robust. Your email sending IPs are separate from your website's CDN IP. Focus on proper email authentication records, such as SPF, DKIM, and DMARC, to prove legitimate sending. This helps maintain a strong sending reputation, regardless of your website's hosting IP issues.
Proactive steps for email health
Given that your website does not send email from the Fastly IP, the blocklist (blacklist) entry should not directly impact your email deliverability. The bounces you observed from your helpdesk software were likely due to an issue with your actual email sending service, which may have had its own IP listed on a blocklist. Once that issue is resolved by your ESP, your email flow should return to normal.
My recommendation is to continue to monitor your actual email sending IPs and domains for any blocklist (or blacklist) entries. This can be done using a dedicated blocklist monitoring service. Regularly checking these is a proactive step in preventing email deliverability issues. It's also wise to keep your website secure to prevent it from becoming a source of malware or phishing, which could lead to its IPs being listed.
To further solidify your email reputation, ensure your domain's email authentication records—Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), and Domain-based Message Authentication, Reporting, and Conformance (DMARC)—are correctly configured and as strict as your sending needs allow. A tighter SPF policy, for instance, helps mail servers verify that legitimate emails are coming from authorized sources.
Example of a robust SPF recordTXT
v=spf1 include:_spf.your-esp.com -all
In summary, while finding your website's IP on a blocklist (or blacklist) can be concerning, it’s often a broader issue with shared hosting infrastructure that does not directly affect your email deliverability. Focus your efforts on your email sending hygiene and authentication to ensure your messages reliably reach the inbox. If you are experiencing deliverability issues, the cause is likely with your email sending IPs and practices, not your website's hosting IP.
Views from the trenches
Best practices
Maintain separate IP addresses for web hosting and email sending to isolate potential issues.
Regularly monitor your actual email sending IPs and domains for blocklist (blacklist) listings.
Implement and enforce strong email authentication protocols like SPF, DKIM, and DMARC.
Ensure your website is secure and free from malware to prevent contributing to shared IP range issues.
Common pitfalls
Assuming a website IP listing directly impacts email deliverability without verifying the bounce source.
Ignoring the security of your website, which can lead to its IP being listed for malicious content.
Using a lax SPF policy, which can allow spoofed emails from blacklisted (blocklisted) IPs to appear legitimate.
Not understanding the different types of blocklists and their specific impact on web vs. email traffic.
Expert tips
If your website is on a shared CDN IP that gets listed, consider it a CDN provider issue to resolve.
Always check the specific IP in bounce messages to determine the true source of deliverability problems.
For static sites, moving to a host with less history of abuse might be a long-term consideration, but not a necessity due to a shared IP blocklist.
Spamhaus is approachable if you address the root cause of the listing and are respectful in your communication.
Expert view
Expert from Email Geeks says to contact Spamhaus directly and provide more details about the specific listing.
2021-06-08 - Email Geeks
Marketer view
Marketer from Email Geeks says that if the entire /24 range is listed for malware distribution and the CDN provider is unresponsive, there isn't much to do other than consider different hosting or not worry too much if email isn't sent from that IP.
Fastly, is listed on a major email blocklist (also known as a blacklist) like 
Spamhaus. Your immediate concern might be about your email deliverability, even if you are certain your website doesn't send emails directly.
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