Automated blocklist fed by fail2ban reports from a network of participating servers. Lists IPs involved in brute-force attacks, SSH scans, and other network intrusion attempts in addition to email ...
Composite zone combining SBL (spam sources), XBL (exploited IPs), and PBL (policy block list) into a single DNSBL query. The most widely deployed IP blocklist in the world. A listing…
Earlier version of the submission RFC. Obsoleted by RFC 6409.
Formalises the greylisting technique where MTAs temporarily reject unknown senders to filter out botnet spam.
Defines the Null MX (0 .) record that explicitly signals a domain accepts no incoming mail, preventing delivery loops.
Defines a third-party endorsement mechanism where a trusted voucher certifies a sender's reputation via DNS.
Operational guide for deploying DKIM: key rotation, selector management, DNS setup, and troubleshooting.
Defines MIME framework for signed and encrypted message parts, foundation for S/MIME and PGP/MIME.
Defines S/MIME 3.2 for signing and encrypting email using X.509 certificates.
Defines the CAPA command that lets POP3 clients discover server capabilities.