Spamhaus

What it means

Spamhaus publishes several DNSBLs. ZEN combines its IP-based lists in one query: the SBL (Spamhaus Blocklist), CSS (Combined Spam Sources), XBL (Exploits Blocklist) and PBL (Policy Blocklist, IPs that should not send mail directly). The DBL (Domain Blocklist) lists domains with poor reputation, queried for the domains in links and headers; Spamhaus notes that ZEN alone gives no protection against bad domains.

Use of its DNSBLs is free for low-volume, non-commercial users; commercial use needs a subscription. Spamhaus defines spam as unsolicited bulk email, about consent rather than content, and recommends confirmed opt-in to avoid spam traps.

Removals start from its IP and Domain Reputation Checker. Spamhaus's CSS listings target current problems, including snowshoe spam and compromised sites.