DMARC.

6 sending domains under DMARC enforcement. 2 still in p=none after 18 months of monitoring. 1 has a misaligned SPF that fails 8% of legitimate mail.

p=none is a policy that protects exactly nothing.

DM-004 · marketing.example.com P=NONE

18mo at p=none. 99.4% aligned. Ready for p=quarantine.

Move to p=quarantine pct=10, watch reports for 14d.