What are the changes to the Spamhaus DBL and how will this affect email marketers?
Michael Ko
Co-founder & CEO, Suped
Published 21 May 2025
Updated 16 Aug 2025
7 min read
Email deliverability is a complex dance, and one of the most critical partners in this performance is Spamhaus. Their various blocklists (or blacklists) are widely adopted by Internet Service Providers (ISPs) and mailbox providers, playing a significant role in determining whether your emails land in the inbox or the spam folder. Staying informed about changes to these lists is crucial for any email marketer aiming for high inbox placement rates.
Recently, Spamhaus announced an important update to its Domain Blocklist (DBL). This change involves a shift towards listing hostnames in addition to entire domains, particularly for cases involving legitimate domains that have been compromised or abused. This refinement aims to offer more granular control and potentially reduce collateral damage for legitimate senders. Understanding these nuances is key to adapting your email strategy effectively.
The Spamhaus DBL has traditionally focused on listing domain names that are actively involved in sending spam, malware, or phishing content. This could include domains used in phishing URLs, malware distribution, or direct spamming. The DBL operates as a DNSBL (Domain Name System Blocklist), allowing mail servers to quickly check if a sending domain's reputation is compromised before accepting mail. This process helps filter out unwanted messages before they reach recipient inboxes.
The significant update is the integration of hostname-level listings for what Spamhaus refers to as "abused-legit" situations. Previously, a listing might apply to an entire domain if any part of it was found to be involved in abusive activities. Now, for specific cases, they can target only the problematic hostname (a subdomain like newsletter.yourdomain.com) instead of the entire root domain (yourdomain.com). This allows for a more precise targeting of bad actors without penalizing unrelated, legitimate email streams from the same primary domain.
An "abused-legit" domain typically refers to a domain that is legitimate in its primary use, but has been compromised, or one of its hostnames is being used to send spam or other malicious content. This could be due to a hacked website, a vulnerable server, or a third-party service misconfiguration. By singling out the offending hostname, Spamhaus aims to minimize the impact on compliant senders who share the same top-level domain. You can learn more about this change on the Spamhaus website.
Impact on email marketers and deliverability
For email marketers, this update is largely positive. The ability of Spamhaus to be more precise with its blocklist (or blacklist) entries means that if a particular subdomain or hostname associated with your brand is compromised, your primary sending domains for marketing or transactional emails might remain unaffected. This reduces the risk of widespread deliverability issues that could arise from a single isolated incident.
This improved precision means less collateral damage. In the past, a blocklist entry for blog.example.com could inadvertently affect marketing.example.com or transactional.example.com. With hostname-specific listings, the impact is contained, allowing other legitimate sending streams to continue uninterrupted. This makes it easier for marketers to isolate and resolve issues without causing widespread disruption to their entire email program.
However, this doesn't mean marketers can relax their guard. It simply shifts the focus to more granular monitoring and management. For comprehensive deliverability, it's still crucial to know which mailbox providers use Spamhaus listings and how this affects your overall deliverability, as well as maintaining a good sender reputation.
Previous DBL approach
Broad impact: A listing often affected the entire primary domain (example.com).
Collateral damage: Legitimate email streams from other subdomains (marketing.example.com) could be blocked.
Removal complexity: Required a comprehensive cleanup of the entire domain to ensure delisting.
New DBL approach (with hostnames)
Targeted impact: Listings can now focus on specific hostnames (spammy.example.com).
Reduced collateral: Other legitimate hostnames under the same domain are less likely to be affected.
Streamlined delisting: Focus can be placed on remediating the specific abused hostname for faster removal.
Adapting your email strategy
This evolution in how Spamhaus lists domains and hostnames means email marketers must adjust their vigilance. It’s no longer enough to monitor just your primary domain; you need to keep a close eye on all hostnames and subdomains used for email sending, website hosting, or any related online activity. A robust blocklist monitoring strategy is more important than ever.
Proactive steps include regular security audits of your web properties and servers, ensuring robust authentication protocols like DMARC, SPF, and DKIM are correctly implemented, and maintaining strict list hygiene. This includes removing unengaged subscribers and leveraging double opt-in to build a clean, engaged audience. This can help you fix issues with emails going to spam.
If you find a specific hostname (or subdomain) associated with your domain on the Spamhaus DBL, the immediate action is to identify the source of the abuse on that particular hostname. This is a more targeted effort than before. Once the issue is resolved, you can then follow Spamhaus' delisting procedures for the specific entry, which should theoretically be quicker and less impactful on your other email operations.
Best practices for avoiding DBL listings
Monitor actively: Use a reliable blocklist monitoring service to track all your sending domains and hostnames.
Segment sending: Utilize separate subdomains for different email types (e.g., marketing, transactional, alerts) to contain any potential issues.
Strengthen security: Regularly audit your website, servers, and email sending platforms for vulnerabilities.
Implement authentication: Ensure your Gmail and Yahoo authentication requirements are met, particularly with DMARC.
Navigating blocklists in a changing landscape
The evolution of the Spamhaus DBL aligns with a broader industry trend towards more intelligent and nuanced spam filtering. Major mailbox providers like Google and Yahoo are increasingly focusing on sender reputation at a granular level, considering factors beyond just IP addresses or root domains. This includes looking at individual hostnames, sending patterns, and user engagement metrics.
While the DBL (and other domain or DNSBL blocklists) are powerful tools, they are part of a larger ecosystem of spam prevention. Mailbox providers use a combination of private internal blacklists, public blocklists, artificial intelligence, and user feedback to determine inbox placement. Therefore, even with more precise blocklisting, a holistic approach to email deliverability remains essential. You can learn more about email blocklists in our in-depth guide.
The ultimate goal for email marketers is to establish and maintain a strong sender reputation. This means consistently sending wanted, engaged-with emails from properly authenticated and secure sending infrastructures. The Spamhaus DBL's shift to hostname-level listings is a positive step, offering more surgical precision in fighting spam while providing legitimate senders with a clearer path to remediation, should issues arise with specific hostnames.
Views from the trenches
Best practices
Actively monitor all subdomains and hostnames for unexpected traffic or abuse patterns.
Segment your email sending infrastructure to isolate different types of email traffic (e.g., marketing, transactional).
Maintain strong cybersecurity practices to prevent compromises of your domains or hostnames.
Implement and correctly configure DMARC, SPF, and DKIM for all sending domains.
Common pitfalls
Overlooking subdomain reputation, assuming only root domains are monitored by blocklists.
Neglecting security updates on web servers or applications that might be linked to your sending domains.
Not having a clear process for identifying and remediating abuse on specific hostnames.
Failing to implement strong email authentication protocols across all email sending points.
Expert tips
Use different subdomains for different types of mail for better deliverability.
A hostname-specific blocklist means less risk of your entire domain being affected by one bad subdomain.
Always prioritize robust security for your sending infrastructure.
Keep your email lists clean; it's the foundation of good deliverability.
Expert view
Expert from Email Geeks says the changes to the DBL are very good news, indicating increased accuracy by listing hostnames instead of just domains.
2021-11-17 - Email Geeks
Expert view
Expert from Email Geeks says this refinement allows for much more precision, enabling the listing of specific abused machines rather than an entire domain.
2021-11-18 - Email Geeks
Embracing evolving email security
The changes to the Spamhaus DBL, particularly the inclusion of hostname-level listings for abused-legit scenarios, mark a positive evolution in email security. This increased precision is good news for legitimate email marketers, as it reduces the likelihood of an entire domain being blocklisted due to isolated incidents on specific subdomains.
However, this also means that email marketers must elevate their diligence. Proactive monitoring of all hostnames, coupled with stringent email authentication and list hygiene practices, will be more important than ever. By adapting to these changes and maintaining robust deliverability practices, marketers can navigate the evolving landscape of spam filtering and ensure their messages consistently reach the inbox.
Spamhaus. Their various blocklists (or blacklists) are widely adopted by Internet Service Providers (ISPs) and mailbox providers, playing a significant role in determining whether your emails land in the inbox or the spam folder. Staying informed about changes to these lists is crucial for any email marketer aiming for high inbox placement rates.
Spamhaus
0Spam
Cisco
NoSolicitado
URIBL
abuse.ro
ALPHANET
Anonmails
Ascams
BLOCKEDSERVERS
Calivent Networks
EFnet
JustSpam
Kempt.net
NordSpam
RV-SOFT Technology
Scientific Spam
Spamikaze
SpamRATS
SPFBL
Suomispam
System 5 Hosting
Team Cymru
Validity
www.blocklist.de Fail2Ban-Reporting Service
ZapBL
2stepback.dk
Fayntic Services
ORB UK
technoirc.org
TechTheft
Gmail and 
Yahoo authentication requirements are met, particularly with DMARC.
