DNS and server checks together
Alongside MX, SPF and DMARC records, suitable MX servers are checked for SMTP, STARTTLS, PTR and forward DNS matching.
Clear SPF and DKIM limits
Nested lookup terms are counted for SPF; unresolved chains may yield incomplete results. A DKIM selector’s public key may be found, but this does not verify a real email signature.
Act on findings
Move from a domain summary to mail details to review missing or apparently incorrect configuration.