CyberStack

Knowledge / identity hardening acsc-glossary

DMARC, DKIM, and SPF

Mail authentication so others cannot cheaply wear your domain. Publish records. Then set a policy that actually rejects.

PHISHING / identity abuse, not a malware class01Lure02Landing03Capture04ReuseControls: phishing-resistant MFA, reporting, mail auth, drills.

SPF lists which servers may send as your domain. DKIM signs messages so the recipient can check they were not stuffed with extras. DMARC lets the domain owner say what to do when those checks fail, and see reports.

Monitor, then quarantine, then reject. p=none forever is a blog post. This cuts domain spoofing. It does not stop a lookalike domain or a mailbox that was actually taken over.

Fact source: ASD's ACSC glossary.