Editing Domain Name System blocklist (section)

=== DNSBL policies ===
Different DNSBLs have different policies. DNSBL policies differ from one another on three fronts:
* '''Goals.''' What does the DNSBL ''seek'' to list? Is it a list of open-relay mail servers or open proxies—or of IP addresses known to send spam—or perhaps of IP addresses belonging to ISPs that harbor spammers?
* '''Nomination.''' How does the DNSBL ''discover'' addresses to list? Does it use nominations submitted by users? Spam-trap addresses or [[honeypot (computing)|honeypot]]s?
* '''Listing lifetime.''' How long does a listing ''last''? Are they automatically expired, or only removed manually? What can the operator of a listed host do to have it delisted?