Spam Filtering (3)

• Rspamd — Email Security System (rspamd.com) tool
  Async C spam and phishing filter: regex rules, RBLs, greylisting, SPF/DKIM/DMARC/ARC, ML scoring
  Email Mail Server #
• OpenDKIM (opendkim.org) tool
  C library plus milter giving sendmail-compatible MTAs DKIM signing and verification, also VBR and ATPS
  Email Mail Server #
• dmarc.org – Domain Message Authentication Reporting & Conformance (dmarc.org) reference
  DMARC email authentication and reporting over SPF/DKIM; policy, alignment, RFC 9989-9991 standards track
  DNS Email #