DIAGNOSTIC PLAYBOOK
SPF void lookups: empty DNS answers in the evaluation chain
Void lookups are DNS queries that return no applicable answer or a name error during SPF evaluation. SPF guidance limits these to protect receivers, so several broken dependencies can cause errors before the main lookup budget is exhausted.
HealthCheck Email editorial team · · Examples are illustrative
How to investigate
- List the DNS-querying mechanisms actually reached for the failing sender.
- Identify NXDOMAIN and empty-answer dependencies, keeping them separate from timeouts.
- Correct misspelled names or retire confirmed obsolete references, then repeat the evaluation for each active sending path.
What this looks like
ILLUSTRATIVE EXAMPLE
A policy has only a few includes, but several targets trigger nonexistent names. Counting the visible mechanisms alone misses the problem.
A mistake to avoid
Do not assume every receiver handles the recommended void-lookup limit identically. Preserve the receiver's reported error with your own lookup results.
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.