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SPF (Sender Policy Framework) is an email authentication standard that lets a domain publish which mail servers are allowed to send email on its behalf, helping receiving mail servers detect spoofed email. This tool checks whether a domain has published a valid SPF record and shows its exact content.
How it works
Enter a plain domain name. The tool looks up its TXT records and specifically checks for one starting with "v=spf1" (SPF records are published as a specially-formatted TXT record, not a separate DNS record type). If more than one SPF record is found, that's flagged as a configuration problem, since a domain should only ever have one.
- Enter domain.
- Click Calculate to see your results.
Examples
A typical SPF record
An SPF record like "v=spf1 include:_spf.example.com -all" tells receiving mail servers to trust only the servers listed under that include, and to reject (-all) mail claiming to be from this domain from any other source.
Who should use it
- Verifying SPF is correctly published after a DNS change.
- Diagnosing email deliverability or spoofing concerns.
Industry applications
- Email deliverability and security
- IT support and DNS administration
Advantages
- Instant check with no software installation.
- Flags the specific "multiple SPF records" misconfiguration, not just presence/absence.
Limitations
- Doesn't validate the SPF record's internal syntax in depth — only detects presence and the multiple-record issue.
Common mistakes to avoid
- Publishing more than one SPF TXT record instead of combining all authorized sources into a single record.
- Assuming SPF alone is sufficient email authentication — pair it with DKIM and DMARC for full protection.
Best practices
- Keep exactly one SPF record per domain, combining all authorized senders into it.
- Review SPF alongside DMARC, since DMARC policy determines what happens when SPF (or DKIM) fails.
Tips
- Pair this with the DMARC Record Checker — SPF alone doesn't tell you what happens when a spoofed email fails the check, DMARC policy does.