Lists IPs operating as botnet drones, open proxies, and compromised hosts. Oriented toward IRC network abuse but used in some mail filter configurations.
Family of IP blocklists covering dynamic IPs (RATS-Dyna), confirmed spam sources (RATS-Spam), and IPs with no PTR record (RATS-NoPtr). Used in SpamAssassin and ...
Swiss academic network blocklist covering spam sources and worm-infected hosts. Used within the Swiss and European academic mail infrastructure.
Formerly listed open relays (RELAYS zone) and uncertain mail sources (UNSURE zone). Has not been actively maintained since the mid-2010s. Still queried by some ...
Lists known Tor exit nodes. Not a spam blocklist but used by some mail servers to flag or reject mail from anonymous Tor network infrastructure.
Brazilian-origin blocklist combining SPF-based sender validation with traditional DNSBL listing. Lists IPs that fail SPF checks or are associated with spam ...
Finnish blocklist covering spam sources identified via local trap networks. Primarily used by Finnish ISPs and regional mail infrastructure.
Registers the full set of standard email header fields with IANA, providing a canonical reference.
Groundbreaking at its time, RFC 974 revolutionized mail routing with DNS integration, but what crucial updates led to its obsolescence by RFC 5321?
Extends DSN and MDN formats to support internationalized addresses.
