DNS Blackhole Lists (DNSBLs)

DNS Blackhole Lists or DNSBLs are a way to filter spam by using Domain Name Service (DNS) records as a database of policies relating to either an IP address or domain name, which can be used to decide whether or not to accept (or label) email. Don't use any of these without testing them first and reading any available listing policy.

DNSBL Lists	This page provides a categorized listing of DNSBLs, including any website, and links to policies and addition and removal pages.
DNSBL Lookup	Several web-based tools can be used to query the most used DNSBLs, or scripts can be downloaded and used locally to check listings.
Use DNSBLs	If you wish to make use of a DNSBL with your mail server, this is where to go.
Manage DNSBLs	A tool as powerful as a DNSBL needs careful handling. Managing a DNSBL properly is now essential, if you are to avoid stale listings and imprecise reasoning.
Provide DNSBLs	Providing a DNSBL can be a more easily managed solution to hosting a local blacklist; you may wish to serve a globally access DNSBL, if you have the resources.

Related

• Filtering Research
• Server Side Spam Filtering
• Client Side Spam Filtering