Why the visible SPF record is not the real count
An SPF record can look short while still expanding into a large dependency tree. An include can reference another policy, which can reference several more. What matters during evaluation is the chain of DNS-querying mechanisms that the receiver may need to process. That is why counting the words in the root TXT record is not enough. A useful audit resolves the chain recursively and records where each dependency entered the policy.
What creates lookup pressure
Includes and redirects are the most obvious sources of recursion, but other SPF mechanisms can also trigger DNS work. Legacy vendors frequently remain authorized long after a migration, so organizations can consume lookup budget for services that no longer send. Duplicate vendor paths are another common source of unnecessary complexity. The objective is not to make the record visually short; it is to preserve every legitimate sender while keeping evaluation deterministic.
Why blind flattening can trade one problem for another
Flattening replaces provider-controlled references with fixed IP ranges. That can reduce DNS recursion, but it also transfers responsibility for keeping those ranges current. If a sender changes its infrastructure and the flattened record is not refreshed, legitimate mail can fail SPF even though the original include would have adapted automatically. Treat flattening as an operational commitment rather than a one-time text transformation.
A safer remediation workflow
Start by inventorying every legitimate sender. Remove stale authorizations only after ownership is verified. Resolve the proposed replacement recursively before publishing it, and preserve enough headroom for predictable growth. After the DNS change propagates, inspect a real delivered message to confirm that the actual envelope sender and sending IP still pass SPF. Mailybox’s SPF Dependency Graph and DNS Change Simulator are designed for this before-and-after workflow.
Verify the evidence
Use the live analysis that matches this workflow instead of relying on a generic status check.