About the Data
The Spamhaus Blocklist identifies IP addresses involved in malicious activities. These IPs are associated with actions such as spam sending, snowshoe spamming, hosting malicious content, providing bulletproof hosting, or hijacking IP space. The dataset includes both individual IPs and IP ranges.
Policy Statement
IP addresses listed on the SBL are flagged as being controlled by, used by, or accessible to spammers and abusers. These addresses are implicated in unsolicited bulk email (UBE) or other internet-based abuses that threaten networks and users. According to [Spamhaus’ definition of “spam”](https://www.spamhaus.org/faqs/general-definitions/), spam is “unsolicited bulk email.” Spamhaus evaluates whether an email constitutes spam based on this definition, without considering the email’s content or legality.
Benefits of this Data
This dataset typically contains 30-40 thousand entries, curated by an OSINT research team, including dedicated investigators and forensics specialists. When combined with other reputation datasets, this blocklist achieves industry-leading catch rates with minimal false positives. Email administrators can use this dataset to reduce inbound spam and malicious email traffic, thereby lowering security risks, email infrastructure costs, and human resource demands.
How to Utilize This Dataset
To maximize the effectiveness of Spamhaus’ data, apply blocklists at crucial stages of the email filtering process. Specifically, use the Spamhaus Blocklist during:
- The initial connection phase to filter the connecting IP.
- The pre-data phase (SMTP transaction) to check the HELO string and Mail From domain.
- Post-email acceptance to examine IP addresses hosting resources found in email headers and body, such as URLs.
Achieve Superior Protection for Free
Each blocklist targets specific behaviors; using a single blocklist limits data effectiveness. Spamhaus offers three additional IP-based blocklists for free:
These IP blocklists can be accessed via ZEN, which combines datasets for faster and easier querying.
While most malicious emails are intercepted during the SMTP transaction, determined bad actors often evade IP detection. To achieve optimal catch rates, also employ domain and hash blocklists post-email acceptance. Spamhaus provides the Domain Blocklist (DBL) for free.
Technical Information
Integrate the data through SMTP server configurations for connection and transaction checks, or use open-source tools like SpamAssassin and Rspamd for content analysis. Plugins are available to minimize setup time for users of Spamhaus Technology’s free Data Query Service. Alternatively, integrate with existing anti-spam platforms with detailed support here. Setup takes minutes, providing instant real-time protection.
Accessing the Data
Spamhaus DNSBLs are available for free for low-volume, non-commercial use. Verify the usage criteria here. Free accounts can be obtained through the affiliated Spamhaus commercial partner, Spamhaus
Best Practices for Maintaining a Positive IP Reputation
Spamhaus safeguards billions of mailboxes globally. To avoid being blacklisted and affecting your email service, adhere to these best practices:
- Secure web forms – Implement captcha or other methods to prevent unauthorized subscriptions and mail bombing.
- Strong Acceptable Use Policy (AUP) – Enforce it promptly upon breach without making exceptions.
- Restrict outbound SMTP traffic – Configure your firewalls to allow outbound SMTP traffic (port 25) only from your internal mail server IP.
- Check infrastructure – Evaluate your ISP and network providers. Refer to reputation statistics on ISPs/networks.
- Double opt-in – Use double opt-in to ensure recipients voluntarily subscribe, preventing spam traps.
- Proper configuration – Ensure hostnames and HELO parameters match, and the reverse DNS (PTR record) points to the same hostname.
Note: Effective management often involves collaboration with network administrators and deliverability specialists.
Removal
SBL Listings
When an SBL listing is created, Spamhaus Project researchers notify the relevant network or hosting companies responsible for that IP. Due to the technical specifics, only these entities can manage SBL removals. General users should consult their Internet Service Provider (ISP) for resolution. Detailed SBL listings can be accessed at [https://check.spamhaus.org/](https://check.spamhaus.org/) using the IP, IP range, or SBL ticket number. Network owners must inform Spamhaus of any changes impacting an SBL listing and request its removal once the original conditions are resolved.
SBL Informational Listings
Informational listings serve as an early warning, indicating that the listed IP is exhibiting suspicious behavior. These listings are advisory and do not result in IP blocking. However, corrective action is necessary to prevent an SBL listing. For detailed information, visit https://check.spamhaus.org/.
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