What should I do if Spamhaus blocklists my agency's IPs and domain?
Matthew Whittaker
Co-founder & CTO, Suped
Published 2 Jun 2025
Updated 17 Aug 2025
7 min read
Finding out your agency's IP addresses and domain have been blocklisted (or blacklisted) by Spamhaus can feel like a sudden blow. It immediately impacts your email deliverability, halting crucial communications for your clients and damaging your agency's reputation. When you manage email sending for numerous companies, identifying the precise cause of such an issue can be a complex task, especially if it's the first time you're facing this challenge.
The key is to approach this systematically, moving from diagnosis to resolution, and then implementing preventative measures. It's not just about getting off the blocklist; it's about understanding why you were listed in the first place and ensuring it doesn't happen again. Many of the fundamental principles of email deliverability apply here, but with the added complexity of managing multiple clients.
The immediate aftermath: confirming the blocklist and assessing impact
The very first action is to confirm the blocklisting and understand its nature. Spamhaus offers a public blocklist lookup tool on their website where you can enter your IP addresses or domain name to verify its status. This will tell you which specific Spamhaus list your assets are on, whether it's the Spamhaus Blocklist (SBL), Exploits Blocklist (XBL), or Domain Blocklist (DBL). Each list targets different types of abuse, and understanding this distinction is crucial for your next steps. For more general insights into why your domain or IP might be blocked, you can refer to this guide on resolving Spamhaus issues.
Once confirmed, the next challenge for an agency is identifying the source of the problematic traffic. When multiple clients share IP addresses or, in some cases, even a common sending domain or tracking domain, pinpointing the exact client or campaign causing the issue can be difficult. Spamhaus typically blocks the entity generating the spam, which, in a shared environment, often means your agency's infrastructure.
You should initiate a delisting request through their official channels. Spamhaus is generally helpful, but they will expect you to address the root cause, not just ask for a removal. They might also provide some details, such as the From address and Subject line of the offending emails. These details are invaluable for tracing the activity back to the responsible client or campaign.
Pinpointing the problem client or campaign
If Spamhaus can only provide general replies, or if the issue seems persistent across multiple campaigns, it indicates a broader problem with your data collection or email sending practices. This is where the agency's operational structure comes into play. If all clients share the same primary domain for click tracking, or a common pool of IPs, it becomes challenging for Spamhaus to differentiate between legitimate and abusive traffic sources originating from your infrastructure. The listing of your agency's domain rather than just an IP suggests a pervasive issue that spans across your operations.
To better isolate issues and protect your overall reputation, consider implementing dedicated sending infrastructure for each client, or at least using unique sub-domains. This allows you to identify problematic clients quickly and contain any negative impact to their specific sending reputation, without jeopardizing your entire agency's deliverability. It's a fundamental step in managing domain reputation in a multi-client setup.
Current approach
Shared infrastructure: All clients send email through the agency's primary domain and shared IPs, including click tracking.
Difficulty in identification: When issues arise, it's hard to isolate the specific client causing the problem.
Broad impact: A single client's poor practices can lead to the entire agency's domain or IP range being blacklisted.
Recommended approach
Dedicated sub-domains/IPs: Assign unique sub-domains or IP addresses for each client or campaign.
Precise isolation: Quickly identify and address problems stemming from individual clients without affecting others.
Containment of risk: A blocklist (blacklist) event affects only the specific sub-domain or IP, not the entire agency.
Implementing solutions and preventing future listings
At the heart of most Spamhaus listings (blacklistings) are issues related to list quality and subscriber consent. Spamhaus explicitly states that general replies often point to a failure to enforce email Confirmed Opt-In (COI) requirements. This means emails are being sent to addresses that never explicitly subscribed or engaged with your clients' content, or worse, they might be spam traps. You can find more details on how to get removed from the Spamhaus blocklist (blacklist) in this comprehensive guide.
If you are using click-tracking URLs for confirmed opt-ins, be aware that Spamhaus robots may follow these links. This can lead to issues if your verification process isn't robust, as automated systems might inadvertently trigger subscriptions that are then flagged as spam. Strengthening your bot detection on landing pages and all links, or changing your verification process entirely, could be necessary. Some senders even resort to multi-factor authentication (MFA) or one-time passwords (OTPs) for email verification to ensure genuine human interaction.
Warning: confirmed opt-in is critical
When Spamhaus indicates issues with Confirmed Opt-In (COI), it's a clear signal that your data collection process has vulnerabilities. This means you might be adding email addresses to your lists without proper, explicit consent, which is a major red flag for anti-spam organizations. Failure to address this fundamentally flawed practice will likely lead to repeated blocklistings, regardless of temporary delisting success. It's not enough to simply request removal from Spamhaus if the underlying problem persists.
The delisting process and long-term strategy
It's crucial to understand that Spamhaus generally expects you to fix the underlying issues before they consider delisting your IP or domain. Simply requesting removal without demonstrating a clear understanding and resolution of the problem will likely result in a rejection, or worse, a quick re-listing. They need to be confident that the spam-generating activity has ceased and that robust measures are in place to prevent recurrence. This is covered more deeply in our guide on Spamhaus causes.
Once you have identified and resolved the root causes, you can proceed with the delisting request. The Spamhaus Blocklist Removal Center provides clear instructions on how to submit a removal request. Be prepared to detail the steps you've taken to remediate the issue, as this strengthens your case for removal. Transparency and a commitment to best practices are key to a successful delisting.
Proactive prevention: beyond delisting
Getting off a blacklist (blocklist) is only half the battle. To prevent future listings, your agency needs to implement a robust, ongoing email deliverability strategy. This includes regular spam trap monitoring, strict list hygiene practices, and ensuring all clients adhere to your agency's anti-spam policy. Building and maintaining a strong sender reputation is a continuous effort, but it safeguards your deliverability and ensures your clients' emails reach the inbox reliably. You can also explore authentication protocols like DMARC, SPF, and DKIM to further protect your sending domains.
Views from the trenches
Best practices
Implement dedicated sub-domains or IPs for each client to isolate potential deliverability issues.
Enforce a strict Confirmed Opt-In (COI) process for all client email lists.
Regularly audit client sending practices to ensure compliance with anti-spam policies.
Proactively monitor your IP and domain reputation on major blocklists, including Spamhaus.
Maintain open communication with Spamhaus during the delisting process and provide requested details promptly.
Common pitfalls
Attempting to delist before fully identifying and fixing the root cause of the blocklisting.
Failing to implement robust bot detection on sign-up and verification links, leading to spam trap issues.
Ignoring general replies from Spamhaus, which often indicate deeper, systemic problems like poor COI.
Using shared IP pools or a single primary domain for multiple clients without proper segmentation.
Not having a clear anti-spam policy or failing to enforce it consistently across all clients.
Expert tips
If Spamhaus blocks your click tracking domain, it likely means multiple clients are causing problems.
Spamhaus robots can follow verification links, so ensure strong bot management for your opt-in process.
Consider using multi-factor authentication (MFA) or One-Time Passwords (OTPs) for email verification.
Ask Spamhaus for specific 'From' addresses and 'Subject' lines of offending emails to identify problematic senders.
Fixing issues before delisting is crucial, otherwise you risk quick re-listing after removal.
Expert view
Expert from Email Geeks says they have extensive experience with Spamhaus and confirms their delisting process is generally helpful.
2023-09-27 - Email Geeks
Marketer view
Marketer from Email Geeks says that general replies from Spamhaus regarding Confirmed Opt-In (COI) issues usually mean there's a problem with the data collection process, allowing unverified email addresses into databases.
2023-09-27 - Email Geeks
Moving forward: maintaining your agency's email reputation
Being blocklisted by Spamhaus is a serious issue for any agency, but it's a manageable one. The path to recovery involves diligent investigation, proactive communication with Spamhaus, and a firm commitment to resolving the underlying causes of the listing. This often means re-evaluating your client onboarding, list management, and email sending practices to ensure they align with industry best practices and anti-spam guidelines. Remember, a blocklist (blacklist) is a signal, not a sentence. It indicates a problem that needs fixing, and by addressing it thoroughly, you can restore your agency's email reputation.
Maintaining an excellent sender reputation is an ongoing process, not a one-time fix. For agencies managing a large number of clients, this means implementing robust policies, educating clients on best practices, and investing in tools or processes that provide granular visibility into sending behavior across all accounts. This proactive approach will help you avoid future blocklistings and ensure consistent, high-quality email delivery for all your clients.
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