How to use the SPF Record Validator/Builder

Validate mode: paste your existing SPF record (get it via `dig TXT yoursite.com`). The tool checks SPF syntax, counts DNS lookups (the 10-lookup limit is enforced by every receiving mail server), and audits your fail policy. Build mode: list the sending services you use (google, mailchimp, sendgrid, etc.) and pick a fail policy. The tool generates a valid SPF record ready to paste into DNS.

Why this tool matters

SPF, DKIM, and DMARC are the three email authentication standards that determine whether your email lands in inbox or spam. Misconfigured SPF (too many lookups, missing services, wrong fail policy) is one of the top causes of deliverability problems. A 1-minute validator prevents weeks of mysterious “marked as spam” tickets.

Common use cases

• Pre-launch email deliverability audit
• Adding a new sending service to your existing SPF
• Troubleshooting “DMARC fail” notifications
• Migrating from one ESP to another without breaking SPF
• Quick SPF review during a security/IT audit
• Helping a client set up email authentication for the first time

The 10-lookup limit

SPF allows a maximum of 10 DNS lookups during validation. Each “include:” counts as a lookup, and many service includes nest more lookups internally (Mailchimp\u2019s include resolves to 6 sub-lookups). Exceed 10 and mail servers return PermError — and your emails fail SPF. Use SPF flatteners or remove unused includes if you hit the limit.

Frequently Asked Questions

What\u2019s the difference between -all, ~all, and ?all?
-all = hard fail (reject mail). ~all = soft fail (mark suspicious but accept). ?all = neutral (no opinion). +all = pass all (insecure — anyone can spoof). Use -all in production after a soft-fail testing period.

Can I have multiple SPF records?
No — RFC 7208 explicitly forbids multiple SPF records. Combine them into one. Many domains have two by accident (legacy plus current); always consolidate.

Does SPF apply to subdomains?
No — SPF records on yoursite.com do not apply to mail.yoursite.com unless you set one there too. Each subdomain needs its own SPF if it sends mail.

Why does Gmail say my SPF is “neutral” even with -all?
SPF only authenticates the envelope sender (Return-Path). The visible From: address could be different — and Gmail evaluates the visible address. Combine SPF with DKIM and DMARC for full coverage.