IP and Domain Reputation Checker
About Spamhaus  |  FAQs  |  News Blog   
Frequently Asked Questions (FAQ)
General Questions
Hacked... Here's help
ISP Spam Issues
Legal Questions
Marketing FAQs
Online Scams
Spamhaus BCL
Spamhaus CSS
Spamhaus DBL
Spamhaus HBL
Spamhaus PBL
Spamhaus SBL
Spamhaus XBL
Spamhaus DROP
 » BGPf FAQs
 » Datafeed FAQs

Spamhaus HBL

DEFINITION: "Hash BlockList" (HBL)

What is the HBL?


How do I use the Spamhaus HBL?
How do I obtain access to the HBL?
Using SpamAssassin and Rspamd with Spamhaus data

DEFINITION: "Hash BlockList" (HBL)

What is the HBL?
What is the Spamhaus Hash Blocklist (HBL)?

To build the the Spamhaus HBL, our software analyzes incoming messages, identifies and normalizes suspect content elements, and for each of them produces a cryptographic hash. That hash is then published as part of the HBL.
  • The HBL is a collection of hashes of malicious or suspicious message elements or "tokens."
  • It stores and queries each token as a cryptographic hash, where each hash is unique to each token.
  • HBL elements include email addresses, cryptocurrency wallets, and both malicious and suspicious files (separate categories).
  • More in-depth technical information can be found in the Spamhaus Technology Ltd documentation of the HBL.
What is the purpose of the HBL?

Identifying such elements in spam messages and then publishing them in HBL provides another means for administrators to filter their inbound email.
  • Mail server software is expected to be able to identify and extract these message elements, compute their cryptographic hashes, and compare it to HBL data.
  • Hash functions are a widely used industry standard which serve two purposes in HBL:
    • It reduces the size of the represented data to a unique, fixed-size string;
    • The hashes cannot be reverted to the original content. That precludes the disclosure of the content in distributed data which may be disallowed by specific privacy laws.


How do I use the Spamhaus HBL?
The HBL list contains hashes, therefore the hash is queried against the list to determine whether the content element has a bad reputation.

Documentation and more in-depth technical details can be foundon the associated Spamhaus Technology Ltd website.

How do I obtain access to the HBL?
The Spamhaus HBL is a commercial product available for use by authorised clients only. Access to it can be requested on the Spamhaus Technology website.

Using SpamAssassin and Rspamd with Spamhaus data
We have developed our datasets with the final goal of being the most compatible with existing software. The two biggest open source antispam projects are SpamAssassin and Rspamd.

To show the best way to use our data with these products, we have created two dedicated Github projects. The projects contain instructions, rulesets, and code to make the best out of our DQS product.

© 1998-2022 The Spamhaus Project SLU. All rights reserved.
Legal  |  Privacy