SPF Flattening Helper
Flatten an SPF record by expanding include: domains (manual paste). Shows approximate DNS lookup count.
Last reviewed by the Radiatus Cloud team
Output
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Flatten an SPF record
An SPF record can only contain a limited number of DNS lookups, and records that include many other domains exceed it and fail. This helper flattens an SPF record by expanding the include domains you paste into their underlying IP ranges, showing the approximate result.
Why the lookup limit forces flattening
SPF authenticates your mail by listing which servers may send for your domain, often by including other providers’ SPF records. But SPF permits only ten DNS lookups when it is evaluated, and each include counts, so a record with many providers silently exceeds the limit and stops working, causing your legitimate mail to fail authentication. Flattening replaces the includes with the actual IP ranges they resolve to, removing the lookups. It is a manual, careful process because the underlying IPs can change, but it is the standard fix for a record that has grown too large.
A fix for oversized records
The tool runs entirely in your browser, so nothing you paste is uploaded, which is exactly what you want when the input is your own security-sensitive data.
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Frequently Asked Questions
Why does an SPF record fail with too many includes?
Because SPF allows only ten DNS lookups when evaluated, and each include counts. A record with many providers exceeds the limit and stops authenticating mail.
What does flattening do?
It replaces the include domains with the actual IP ranges they resolve to, removing the DNS lookups so the record stays within the limit.
What is the downside of flattening?
The underlying IP ranges can change, so a flattened record must be maintained. It is a careful, manual fix rather than a set-and-forget one.
When do I need to flatten?
When your SPF record includes so many providers that it exceeds the ten-lookup limit and legitimate mail starts failing authentication.
Is my record uploaded?
No. The expansion works from what you paste, in your browser.
Privacy & Security
Processed locally in your browser. No DNS lookups are performed automatically.
How to Use
Paste your SPF record and the included domain SPF records to generate a flattened output.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.
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SecurityMeasure password strength by entropy and pattern analysis rather than character-class rules. Checked entirely in your browser.
Password Generator
SecurityGenerate strong random passwords and passphrases in your browser using the Web Crypto API. Nothing is transmitted, logged or stored.
Hash Generator
SecurityGenerate MD5, SHA-1, SHA-256 and SHA-512 hashes in your browser. Compare checksums and verify file integrity with nothing uploaded to a server.