Use this SPF checker workflow to validate your domain's SPF DNS record and confirm which servers can send on your behalf.

Quick answer

An SPF checker confirms whether your SPF record is valid, whether authorized senders are complete, and whether include chains are likely to exceed DNS lookup limits.

What an SPF checker should confirm

  • Your domain publishes an SPF TXT record
  • Authorized senders are explicitly listed
  • Includes are valid and not overly complex
  • Policy ending ( or ) matches your enforcement goal

How to check SPF records

  1. Query your root domain SPF TXT record
  2. Review all and or mechanisms
  3. Validate your final qualifier ( vs )
  4. Re-test after DNS updates propagate

SPF best practices for production domains

  • Publish exactly one SPF record per domain.
  • Keep chains as short as possible.
  • Remove deprecated senders quickly after migrations.
  • Align SPF updates with DKIM/DMARC policy reviews.
  • Re-run checks after every DNS change.

Common SPF mistakes

Multiple SPF TXT records

A domain should publish one SPF policy record. Multiple SPF records often cause lookup failures and inconsistent mailbox provider behavior.

Too many DNS lookups

SPF has a DNS-lookup limit. Nested chains can exceed that limit and cause soft fails.

Unsafe policy mode for production

If you are ready to enforce policy, move from monitoring () toward stricter enforcement () after validation.

Move from manual checks to automation

MailSlurp supports DNS and authentication monitoring for production workflows. Start with DMARC, SPF, and DKIM monitoring and connect alerts into your delivery process.