xbl.selwerd.cx (eXtreme spam Blocking List) Providers that let users spam selwerd.nl, selwerd.cx, flits.rug.nl and other spamtraps and ignore reports, host spamvertized pages or pages selling spamware get listed. Using xbl.selwerd.cx risks missing a lot of legitimate e-mail. http://www.selwerd.cx/xbl/

Open Relay Database (ORDB) A validated database of mail servers that permit third-party relay. Also in Francais, Nederlands and Dansk. http://www.ordb.org/

Spam Prevention Early Warning System (SPEWS) SPEWS maintains a list of known spam sources and spam friendly hosts so that e-mail can be rejected from these problem sites. http://www.spews.org/

MAPS Realtime Blackhole List (RBL) Lists email sites which have refused to limit their relaying, leaving the potential for their use as spam gateways. http://mail-abuse.org/rbl/

MAPS Dial-up User List (DUL) An IP blacklist of dialup-using "stealth" spammers and email trespassers. http://mail-abuse.org/dul/

OpenRBL DNS Lookup Enter an IP address or a hostname to find out which blacklists (if any) list it. http://openrbl.org/

SpamCop - Blocking List Information This list contains IP addresses which have been reported to SpamCop as carriers of spam (source of e-mail or verified, open relay). Some of these reports now come from spamtraps (email addresses used strictly to receive spam). http://spamcop.net/bl.shtml

ip4r (DNSBL-style) DNS lookups List, in table form, of blacklists. Includes table with the name of the blacklists, their lookup domains, the IP that is returned in case of a match and a description. http://www.declude.com/junkmail/support/ip4r.htm

Relays.visi.com Blacklist of open relaying mail servers that have recently transmitted spam. http://relays.visi.com/

Spamhaus Block List (SBL) All IPs on the SBL belong to known spammers, spam gangs, or spam support services. The SBL includes IPs from both the ROKSO database and IPs of spam services listed in the Spamhaus database. http://www.spamhaus.org/sbl/

The Spamhaus Project Register of Known Spam Operations (ROKSO) The Spamhaus Project's Register Of Known Spam Operations (ROKSO) Database. ROKSO collates evidence on known hard-line spam outfits that have been thrown off Internet Service Providers over three times. http://www.spamhaus.org/rokso/

Blacklists Compared Weekly reports of DNS blacklists lookups of IP addresses (and reverse DNS lookups) that made SMTP connections to the San Diego Supercomputer Center on that week. Useful for getting a grasp of the size of the various blacklists. Maintained by Jeff Makey. http://www.sdsc.edu/~jeff/spam/Blacklists_Compared.html

Five Ten - Local Black Holes Blacklist that includes dialup equivalent ip addresses, individual spam sources, netblocks that refuse to remove spammers, bulk mailers that don't require confirmed opt-in, output servers from multi-stage open relay chains and single stage open relays not listed on ORBZ. http://www.five-ten-sg.com/blackhole.php

Blitzed IRC Network (OPM.BLITZED.ORG) A dnsbl of open proxies (HTTP, Socks and wingate), populated by IRC connection scanners and spamtraps. http://www.blitzed.org/proxy/

Clueless Mailers Offers background information on the worst of the new Internet abusers. http://www.cluelessmailers.org/

Spambag.org Personal (DNSBL) list of abusive networks that the author blocks from sending mail or accessing his web servers. http://www.spambag.org/

Spam Filtering @ Monkeys.Com - Unsecured Proxies List Lists open proxies. An open proxy of one kind or another is bad because spammers may use it to send out massive amounts of unsolicited bulk e-mail spam. http://www.monkeys.com/anti-spam/filtering/proxies.html

rfc-ignorant.org The home for domains who don't play by the rules. A number of lists (at present "dsn", "abuse", "postmaster", "whois" and "ipwhois") which contain domains or IP networks whose administrators choose not to obey the RFC's, the building block "rules" of the net. http://www.rfc-ignorant.org/

Not Just Another BlackList (NJABL.ORG) Spam blocking blacklist of open relays, dial-ups, and direct spam sources. http://njabl.org/

Spambag of the Month Makes examples of people who feel the need to send unsolicited emails. Sample emails and follow-up information. http://www.spambag.net/