Professional, fully supported, use of the Spamhaus DNSBLs (SBL, XBL, PBL and the combined ZEN lists) is available for use by entities of all size. The preferred method is to set up a local server to house the Spamhaus Datafeed Service. Your email system sends queries locally to a private server on your own network which is kept up to date continuously via Rsync. For service pricing see the Data Feed service page.
Spamhaus DNSBL Data Feed Service
Data Feed is a service designed for users with high DNSBL query requirements, such as corporate networks and ISPs. It provides data synchronizations of the Spamhaus Blocklists (SBL, XBL, PBL and DROP) to a local DNS server on your network every 30 minutes.
A Data Feed eliminates latency problems for mail servers and very significantly speeds email filtering up. It enables more effective filtering and in-depth checks (see document: Effective Spam Filtering) to be made on incoming mail (such as also checking IP addresses of websites in spam messages against the SBL, in addition to the connecting IPs).
The Data Feed service has strong advantages over the traditional scheme based on DNS queries over the public DNS infrastructure: 1) it is still based on DNS queries, so there is little difference (if any) in your mail servers configuration; 2) all DNS queries are local, so the turnaround time is short and entirely under your control; this means shorter transit times for messages; 3) as far as DNSBL checks are concerned, the mail flow will not be affected by any problem on the network or on the Spamhaus servers; 4) the service comes with a Service Agreement contract and Support.
Synchronization Method and Format
The Data Feed service utilizes Rsync as the data synchronization method and Rbldnsd to serve the DNSBL zones. Rbldnsd is a DNS server specifically designed for fast loading and serving of large DNSBLs, and which can also where necessary run on the same IP as BIND.
An installation manual for setting up the Data Feed service using Rsync and Rbldnsd is supplied with the Data Feed service. (Both Rsync and Rbldnsd are free and are also now available for both UNIX and Windows servers.)
Service Pricing
The Data Feed service is supplied as a yearly subscription, with a Service Level Agreement and Technical Support. Pricing is based on the total number of Email Users your organization provides email service for, and the type of organization (commercial or non-profit).