DNS based blocklists

The following blocklists were recommended by 'DocSnyder' in de.admin.net-abuse.mail:

# Relays
relays.ordb.org                # all usable
opm.blitzed.org
dnsbl.njabl.org
list.dsbl.org
relays.visi.com

# Multihops
multihop.dsbl.org              # only use for accounts with LOTS of spam

# Dialups
dul.dnsbl.sorbs.net            # stops most worms

# Spam-in-progress
client.dnsbl.docsnyder.de
xbl.spamhaus.org               # "no false positives yet"
bl.spamcop.net                 # only use for accounts with LOTS of spam

# SPEWS
l1.spews.dnsbl.sorbs.net       # hardcore spammers
l2.spews.dnsbl.sorbs.net       # their assistants

# Hardcore spammers
sbl.spamhaus.org               # Spamhaus Block List
blacklist.spambag.org
spamfriendly.dnsbl.docsnyder.de   # manually maintained

# RHSBL
sender.rhsbl.docsnyder.de      # manually maintained
helo.rhsbl.docsnyder.de        # manually maintained
rhsbl.sorbs.net                # experimental

# RFC-ignorant (DNSBL)
ipwhois.rfc-ignorant.org       # experimental

# RFC-ignorant (RHSBL)
whois.rfc-ignorant.org         # experimental
postmaster.rfc-ignorant.org    # experimental
abuse.rfc-ignorant.org         # experimental
dsn.rfc-ignorant.org           # experimental

dnsbl.au hosts many blocklists and blocklist mirrors: http://dnsbl.net.au/status.php

Anti-Spam Resources:
jwSpamSpy is our spam filter (free evaluation version available for download)
How to trace senders of spam: Most spam emails arrive with fake return addresses. Here's some information that will help you trace the person responsible and who to complain to.

Anti-spam domain blacklist – list of domains that I refuse to receive mail from
Recent additions to domain blacklist (with whois details)

AOL dial-up address ranges and mail servers
Dynamic IP addresses