Pre-change safety

Email DNS Change Simulator

Test a proposed SPF or authentication change before publishing it to production DNS.

spf simulatordns change simulatorspf record testemail dns migration
Compare current SPF with a proposed recordRuns the proposed policy through the same recursive evaluator without publishing anything.

What this analysis does

Compare the current public state with a proposed configuration and see lookup pressure, policy changes and likely authentication consequences before making the change.

How to use the result

Use real evidence

Paste the exact domain, header, message or configuration. The result is only as useful as the evidence supplied.

Review the findings

Mailybox separates observations from inferred causes so you can see what is known and what still needs verification.

Retest after changes

Email authentication and routing are stateful. Re-run the analysis after publishing a fix.

Interpretation matters

Email systems combine DNS, message-level evidence, provider policy and intermediate infrastructure. A single passing check is not proof that every message will deliver, and a single warning is not proof that a domain is misconfigured. Mailybox is designed to expose the evidence and the relationship between signals so the next action is clear.