DKIM rotation without delivery impact
Overview
Rotate DKIM keys periodically—overlap selectors to avoid signing gaps.
Method
Publish new selector with key; verify pass in DMARC reports; swap default sending preference; retire old after 7 days healthy traffic.
Pitfalls
Deleting old DNS TXT while messages still queued at old MTA—coordinate TTL.
Document
Runbook screenshot of DNS diff stored per client.
Automation
Calendar reminder 2× yearly unless vendor mandates faster.
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