The SPF ten-DNS-lookup limit is evaluated during recipient processing, so a record can look syntactically correct and still return permerror. Simplify by reducing unnecessary includes and sender paths; do not blindly flatten dynamic provider records into IPs that will go stale.
Count mechanisms that trigger DNS queries
Include, a, mx, ptr, exists and redirect can consume lookup budget; nested includes count too.
Inventory real senders
List the services that actually send as the domain. Remove abandoned SaaS includes before optimizing a record for systems no longer used.
Prefer provider-specific subdomains where useful
Separating transactional, marketing or regional senders can reduce one root record’s complexity and clarify ownership.
Treat flattening as maintained data
If you must flatten, define refresh frequency and failure monitoring. Provider IP ranges can change without warning.
Check DMARC before declaring success
A passing SPF record is useful only if the authenticated domain aligns or DKIM provides aligned authentication.
Test from each sender
Send representative messages through every retained platform and inspect Authentication-Results for SPF result and evaluated identity.
Use the multiple-sender SPF guide and validate alignment with the DKIM guide.
Draw the SPF dependency tree before editing DNS
Expand every include and redirect into a small tree and count lookup-producing mechanisms along each path. Mark who owns every branch and whether the sender is still active. This often reveals that the safest fix is removing an abandoned service or giving one sender a subdomain, not compressing a record whose complexity reflects years of untracked vendors.