DNSBL Usage Terms - The Spamhaus Project

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Spamhaus DNSBL Usage Terms

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Datafeed Service

Datafeed FAQs

If you are using the Spamhaus DNSBLs (SBL, XBL, PBL, DBL or ZEN) to filter your mail you need to know whether you qualify for free use or not. This is especially important in a corporate environment.

Too often staff set their company's mail server to use the Spamhaus DNSBLs without checking these Usage Terms to see if their company qualifies for free use. Some weeks or months down the line this then causes problems when Spamhaus's public servers detect a high query volume from a particular source and firewall it from the public DNSBL network.

Free Use is satisfactory for private mail systems with low traffic, but mail server administrators are responsible for ensuring their servers remain constantly below the free use limits. Professional Use (known as the Datafeed Service) provides a completely different and dependable level of service, using your choice of either private dedicated DNSBL servers or rsync data delivery direct to your network, and is backed with an SLA and technical support.

Caution: If your usage should exceed the free use terms your access to Spamhaus's public DNSBL servers is very likely to be cut off without warning.

Free Use

Spamhaus serves billions of DNSBL queries to the world every day, free of charge, from its public DNSBL servers. This free public DNSBL service is sustained thanks to donations of equipment and bandwidth and is backed financially by an autonomous commercial service that delivers Spamhaus data to ISPs, commercial networks and spam filter services. To qualify for free Spamhaus DNSBL query service, mail server operators must ensure they meet the criteria for free use.

Use of the Spamhaus DNSBLs via DNS queries to our public DNSBL servers is free of charge if you meet all three of the following criteria:

1) Your use of the Spamhaus DNSBLs is non-commercial*,
    and
2) Your email traffic is less than 100,000 SMTP connections
    per day, and
3) Your DNSBL query volume is less than 300,000 queries
    per day.

If you do not fit all three of these criteria then please do not use our public DNSBL servers, instead see 'Professional Use'.

If you are in any doubt as to whether you fit within our free use criteria, or think you may be likely to soon exceed our free use criteria, please switch to 'Professional Use'.

Spamhaus monitors use of its public DNSBL servers to identify installations exceeding the free use criteria in order to prevent a minority of heavy users from degrading the quality of the service to all other users of our free public DNSBL servers.

Professional Use

Use of the Spamhaus DNSBLs by organizations and networks with email traffic likely to exceed the Free Use limits, or by ISPs or commercial spam filter services, requires a subscription to the Spamhaus DNSBL Datafeed Service, a service designed for users with professional DNSBL requirements.

The Datafeed Service provides two options of professional service (Datafeed Query Service or Datafeed Rsync Service), both delivering super-fast realtime responses to your mail server and both backed with support and a service contract.

If unsure, you can try the Datafeed Service free for 30 days before deciding to subscribe to it. For more information see:

Datafeed Service

*Definition: "non-commercial use" is use for any purpose other than as part or all of a product or service that is resold, or for use of which a fee is charged. For example, using our DNSBLs in a commercial spam filtering appliance that is then sold to others requires a data feed, regardless of use volume. The same is true of commercial spam filtering software and commercial spam filtering services.

A company that uses our DNSBLs solely to filter their own email qualifies as a non-commercial user and may use our free public DNSBLs if that company's email volume and DNSBL query volume is below the free use limits. The same is true for any non-profit organization, school, religious organization, or private individual who operates their own mail server.