What is Spamhaus and how do they use traps?
Still have a question, spotted an error, or have a better explanation or a source we should cite?
Spamhaus is a nonprofit organization that tracks and publishes information about spam sources, malicious domains, and known-bad IP addresses. It's not a government body, but its blocklists are trusted by a huge portion of internet infrastructure. When your IP or domain lands on a Spamhaus list, many mail servers will reject your email outright.
The lists Spamhaus maintains
Spamhaus runs several different lists. The most important ones for email senders:
SBL (Spamhaus Blocklist). IPs and domains directly involved in spam operations.
XBL (Exploits Block List). compromised machines being used to send spam without the owner's knowledge.
DBL (Domain Block List). domains found in spam content. Your domain can land here even if you're not listed in the SBL.
ZEN. a combined list. Most mail server operators just query ZEN rather than each list individually.
How spam traps fit in
Spamhaus operates its own trap network, often called the "Project Honey Pot" adjacent system (though the two are distinct). They seed pristine honeypot addresses in places spammers harvest from, and they maintain recycled trap addresses from older domains and defunct mailboxes they've taken over. When a sender's IP hits their traps, that data feeds into listing decisions.
One or two hits might just be noted. A pattern of hits, especially to pristine honeypots, is much more likely to trigger a listing. Their process isn't fully public, which is by design. The goal is to list deliberate spammers, not to accidentally catch legitimate senders who hit one old recycled address.
If you get listed
Spamhaus has a delisting process for each of their lists. For the SBL, you'll need to demonstrate you've fixed the underlying problem (cleaned the list, removed the bad sending source) before they'll delist you. The turnaround varies. You can check your current status with our free blocklist checker, and if you're dealing with an active listing and need help navigating the process, the Review My Emails SOS hotline is there: reviewmyemails.com/sos.
Contributors
Who worked on this answer
Every name links to their profile. Every company links to their site. Real people, real accountability.
