Which blocklists have shut down or are defunct?

The blocklist landscape changes constantly. Lists shut down, get acquired, or become unmaintained. Using defunct lists in your spam filtering can cause delivery problems when they return wildcard responses.

Recently defunct (2024-2025):

Long defunct (historical reference):

Why defunct lists matter:

• When lists shut down, they sometimes return wildcard **DNS** responses
• This can cause ALL mail to be blocked if the defunct list is still queried
• Regularly audit which blocklists your mail systems query
• Remove any defunct lists from your configuration immediately

How to check if a list is active:

• Query a known-good IP (like Google's 8.8.8.8) - should return NXDOMAIN
• Check dnsbl.com for status updates
• Verify the list's website is still operational

A dead blocklist can cause more damage than a live one. When the lighthouse keeper abandons their post but leaves the light on, ships start running aground because the signal no longer means what they think it means.