DIAGNOSTIC PLAYBOOK
SPF on a delegated subdomain: find the right DNS owner
A delegated subdomain can have its own authoritative DNS service. Editing a record in the parent zone may not change the SPF answer receivers obtain for that name.
HealthCheck Email editorial team · · Examples are illustrative
How to investigate
- Trace the subdomain's NS delegation and identify the authoritative servers that answer its TXT query.
- Compare the live answer with the intended policy and locate the account that controls the delegated zone.
- Make the approved change at the authoritative owner and verify from outside the parent DNS dashboard.
What this looks like
ILLUSTRATIVE EXAMPLE
A marketing subdomain is delegated to a service. Adding a TXT record under the parent zone appears successful in the editor but does not update the delegated answer.
A mistake to avoid
Do not remove a delegation to force an SPF change without checking every service hosted beneath it. Other records may depend on the same delegation.
Keep the result in context
SPF evaluates the SMTP client against the envelope sender domain, or the HELO identity in the applicable case. A record lookup can identify publication problems; a message result also needs the actual sending IP and identity. Keep those inputs with your investigation.
Take the next step
Use the related check to gather evidence, then compare it with the affected message or service. Keep the result and time with your notes so a later change can be distinguished from the original problem.
Sources and further reading
The protocol references below explain the underlying behavior. Your sending or DNS provider supplies the account-specific settings for its service.