🚫 RBL & Domain Blocklist Directory

Real-time Blocklists (RBLs) and Domain Block Lists (DBLs) are DNS-based databases used by mail servers to identify known spam sources. The TamingDNS Blacklist Checker queries every live blocklist listed here; entries marked defunct are kept for reference and are no longer queried. Each entry below includes the listing criteria, return codes, and step-by-step delisting instructions.

How Blocklist Lookups Work

For IP lookups, the sending IP is reversed and prepended to the DNSBL hostname. For example, to check if 203.0.113.5 is on Spamhaus ZEN, a DNS A query is made for 5.113.0.203.zen.spamhaus.org. If an A record is returned, the IP is listed. The specific 127.x.x.x return value indicates which sub-list triggered the listing.

Domain blocklists (DBLs) work similarly but use the domain name directly: example.com.dbl.spamhaus.org.

🌐 IP-Based Blocklists (15)

Queried against the sending IP address of each mail server.

Spamhaus ZEN
zen.spamhaus.org
ZEN bundles four Spamhaus lists into one query: SBL (known spammers), CSS (snows…
Barracuda
b.barracudacentral.org
IP reputation list run by Barracuda Networks. Barracuda describes the underlying…
SpamCop
bl.spamcop.net
Cisco Talos runs SpamCop on direct user reports. Anyone with a SpamCop account c…
PSBL
psbl.surriel.com
PSBL is a conservative trap-fed blocklist. The trigger is straightforward: send …
UCEPROTECT L1
dnsbl-1.uceprotect.net
Level 1 is the per-IP layer of UCEPROTECT. One IP, one listing. Entries roll off…
UCEPROTECT L2
dnsbl-2.uceprotect.net
Level 2 lists a whole allocation once enough addresses inside it trip Level 1. T…
UCEPROTECT L3
dnsbl-3.uceprotect.net
Level 3 lists every IP belonging to an entire autonomous system. UCEPROTECT calc…
Mailspike BL
bl.mailspike.net
Mailspike scores sending IPs on a reputation scale from L5 (worst) to H5 (excell…
NORDSPAM
bl.nordspam.com
NordSpam publishes a small IP blocklist alongside its domain list, free for comm…
WPBL Defunct 2024
db.wpbl.info
WPBL pooled complaint data from a set of participating mail servers and weighted…
CBL Abuseat
cbl.abuseat.org
The Composite Blocking List flags IPs whose sending pattern looks automated: com…
Spamhaus PBL
pbl.spamhaus.org
The Policy Block List is not a spam list. It is a directory of IP ranges that th…
GBUDB
truncate.gbudb.net
GBUDB scores IPs on long-running behaviour rather than individual incidents. The…
S5H
all.s5h.net
s5h.net is a small, hand-curated DNSBL run by a single security researcher. It c…
SPFBL
dnsbl.spfbl.net
SPFBL is a Brazilian-origin DNSBL that mixes IP reputation, SPF validation resul…

🔗 Domain-Based Blocklists (5)

Queried against the domain name. Checks domain reputation regardless of sending IP.

Spamhaus DBL
dbl.spamhaus.org
The Domain Block List rates the domain itself, not the IP that sent the mail. It…
SURBL Multi
multi.surbl.org
SURBL tracks the URLs inside spam, not the IPs sending it. The "multi" zone is t…
URIBL Black
black.uribl.com
URIBL Black is the strict tier of the URIBL family. Every entry is manually revi…
Abuseat DBL
dbl.abuseat.org
The domain-side companion to the abuseat CBL. abuseat no longer runs independent…
NordSpam DBL
dbl.nordspam.com
NordSpam's domain reputation feed. Its data carries most weight inside Nordic an…

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📖 Further reading