- What is SPF flattening?
- SPF flattening replaces the 'include' mechanisms in your SPF record with the actual IP addresses they resolve to. This removes the extra DNS lookups those includes cost, helping you stay under SPF's limits.
- How do I use this tool?
- Enter your domain and the tool fetches your published SPF record, resolves every include down to its IP4 and IP6 addresses, and returns a flattened record. If the result exceeds 512 bytes it is split into a parent record plus one or more child records you can chain together.
- Why does SPF flattening matter?
- SPF permits a maximum of 10 DNS lookups per evaluation, and exceeding it causes a 'permerror' that can make legitimate mail fail authentication. Flattening collapses those lookups into raw IPs so you stay within the limit.
- How do I apply the flattened result?
- Copy the generated parent record into your domain's SPF TXT record, and publish any child records under the hostnames shown so the 'include' chain resolves. Keep the trailing '-all' or '~all' policy from your original record unless you intend to change enforcement.
- What is a limitation of flattened SPF records?
- Because it hardcodes IPs, a flattened record no longer updates automatically when a provider like your email host changes its sending IPs. You must re-run the flattening and republish whenever those upstream addresses change, or mail may start failing SPF.