How to check if SPF is too complex
Learn how to spot overly complex SPF records, recursive includes, and DNS lookup limit risks.
Why SPF complexity matters
SPF has a practical lookup limit of 10 DNS-based mechanisms and modifiers. A policy that becomes too complex can cause evaluation problems or outright failures.
This is especially common when multiple third-party senders are added over time without cleanup.
Warning signs
- Large numbers of include statements
- Nested includes that reference more includes
- Use of redirect without understanding the final effective policy
- Old services still present in the record
What to do
Review who actually sends mail for the domain, remove unused services, and avoid blindly stacking new include statements forever.
A good SPF checker should follow includes and redirects so you can estimate the real lookup count.