SummaryA flattened SPF record is a maintained policy, not a permanent snapshot. Compare update handling, validation, recovery and supported rules before choosing how to manage it.
In this guide
What SPF flattening changes
A conventional SPF policy can refer to another policy with include:. That provider may refer to more policies in turn. Flattening resolves supported rules into address ranges so that a receiver can compare an IP address without following the same chain.
For a deliberately simple, fictional example, imagine these source policies:
studio.example:
v=spf1 include:mail.example -all
mail.example:
v=spf1 ip4:192.0.2.0/24 ip6:2001:db8:100::/48 -allThe equivalent direct address policy for this example would be:
v=spf1 ip4:192.0.2.0/24 ip6:2001:db8:100::/48 -allThe ip4 and ip6 mechanisms do not use the ten-term DNS lookup budget. A managed service may still use an include or another hosted reference, so the final published arrangement also needs checking. Google’s SPF record reference explains the distinction between address rules and DNS-based mechanisms.
When flattening is worth considering
Flattening can be useful when a policy depends on several necessary providers, nested includes create lookup pressure, and someone needs to keep those authorisations current. It is also a maintenance decision: you are choosing who tracks changes and validates the result.
A simple policy with ample lookup headroom may be easier to keep in the provider’s recommended form. First remove confirmed obsolete authorisations and check whether each service actually needs an entry at that DNS name. Do not introduce another dependency solely to replace a policy that is already straightforward to maintain.
If you already have an evaluation error, diagnose it with our lookup-limit guide. A lookup-limit error can be addressed by flattening supported references. Invalid syntax, broken references and unsupported rules require a different correction.
Manual and automated maintenance compared
| Responsibility | Manual flattening | Automated management |
|---|---|---|
| Provider changes | A person or an independently maintained process must detect and apply them. | The service follows supported source policies. Confirm its update behaviour. |
| Validation | You must check addresses, rule meaning, record size and actual mail. | Review what the service validates; retain your own message tests. |
| DNS failures | A failed query must not be mistaken for an empty sending list. | Check whether the service retains a verified policy when a source is unavailable. |
| Recovery | Keep an earlier working policy and a documented restoration process. | Confirm policy history, restoration options and how you would leave the service. |
| Adding services | Update the intended source list and repeat validation. | You still need to select or configure the new sender deliberately. |
Automation transfers some recurring work; it does not remove ownership of which services should be authorised. Nor does the word “automatic” establish how quickly updates occur. Use the actual service documentation when assessing those expectations. Read when provider SPF updates require a DNS change for the distinction between native includes and copied address lists.
The risks in a copied address list
Suppose a provider adds a new sending range next month. A snapshot taken today will not authorise it. If the provider retires a range and it stays in your copy, that obsolete authorisation remains until someone removes it. Keeping the source-policy list lets you trace where every range came from. For the contrast with ordinary includes, see why SPF results can change without a DNS edit.
Flattening must preserve policy behaviour, not just collect every IP mentioned anywhere. Positive and negative rules, overlapping ranges, IPv6, nested results and rule ordering need deliberate treatment. Some mechanisms depend on message-specific information and cannot be represented by one fixed list.
Also check the resulting DNS record size. A long list can create publication or DNS-response problems. Several text strings inside one TXT record are possible; multiple independent SPF records are not a size workaround. RFC 7208 discusses record-size considerations.
How Emailmetry flattens SPF
Emailmetry flattens supported SPF references into sending IP ranges and keeps them current. Its published safeguards describe checks for supported policy behaviour, validation before publication, retention of the last validated policy when provider DNS cannot be verified, and policy history for recovery. DNS caching still affects how quickly a changed or restored record reaches receivers.
Emailmetry works with supported SPF records across email services. Records already over the ten-lookup limit can be flattened when their references resolve into supported IP ranges. Invalid syntax and broken references need separate correction. Check compatibility for your actual policy.
Emailmetry automatically flattens SPF; it does not relay messages or configure a provider’s DKIM signing. You remain responsible for adding or removing selected senders and checking DMARC alignment.
A practical migration checklist
- Inventory the active services and the exact domains they use for envelope senders.
- Save the working DNS policy, TTL, source references and received-message baseline.
- Check compatibility and understand the proposed DNS record before replacing anything.
- Publish during a period when someone can test and investigate unexpected failures.
- Send from every important workflow and retain the receiving system’s SPF, DKIM and DMARC results.
- Record who owns future provider changes and how to restore an independently maintained policy if needed.
Start with an SPF inspection. If SPF flattening fits your record, review Emailmetry pricing and start a free trial.