The delivability depends on the actual behaviour of the sender and not only the presence of three DNS records.
Steps.
- Identify the sender — Note envelope-(3) and From.
- Check SPF – The path of shipment must be authorized.
- Check for DKIM — Control selector and signature.
- Check DMARC — Analyze alignment and policy.
Commands
nslookup -type=txt example.comnslookup -type=txt _dmarc.example.comKey takeaways
- Avoid multiple separate SPF records.
- Pass DMARC to the mlan only after sufficient observation.