Email dan DNS for Fly.io
medium6 checks
Email authentication protects the brand, not the website. SPF, DMARC, DKIM, DNSSEC and CAA are cheap controls that stop spoofing and rogue certificates.
What Fly.io must have
- SPF record ending in -all with every legitimate sender listed
- DMARC published, moving from p=none to quarantine then reject
- DKIM signing enabled on the mail provider
- DNSSEC signed at the registrar
- CAA record restricting which CAs may issue certificates
- MTA-STS and TLS-RPT for inbound mail
How to fix it
- 1Publish DMARC in monitoring mode first, then tighten after reviewing reports
- 2Add CAA for the CA you actually use, usually letsencrypt.org
Fly.io context
Edge application platform running containers close to users.
Secrets are environment variables; rotate them and avoid logging the environment.