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SPF flattening is the process of converting an SPF record that relies on multiple third-party include statements into a simplified, optimized list of authorized sending IP addresses. Instead of forcing receiving mail servers to perform many DNS lookups during SPF evaluation, a flattened SPF record publishes the resolved IP ranges directly in DNS.
This matters because modern organizations rarely send mail from one system. A typical domain may use Google Workspace, Salesforce, Mailchimp, an Email Security Gateway, CRM platforms, ticketing tools such as Atlassian, and outbound SMTP services. Each vendor often asks you to add its own SPF include. Over time, the SPF record grows, teams nest includes unintentionally, and the domain approaches the SPF 10-lookup limitation.
SPF flattening helps maintain SPF compliance while preserving email authentication accuracy. A well-managed flattened SPF record can identify authorized senders without triggering failures caused by excessive DNS lookups.
A traditional SPF record might contain multiple include mechanisms, an mx mechanism, a redirect mechanism, or a mechanism reference. Under RFC 7208, SPF allows only 10 DNS lookups per SPF check. If a domain exceeds that threshold, the result can be permerror, which can damage email deliverability and weaken SPF authentication.
Many administrators refer to this operationally as the SPF 10-record limit, although the technical issue is the SPF 10-lookup limitation. The practical result is the same: too many DNS lookups can cause valid mail to fail authentication.
The problem becomes harder to see when service provider includes contain their own includes. For example, Google Workspace, Salesforce, Mailchimp, and other email services may publish SPF records that reference additional domains. When teams nest includes, they may not realize how many DNS lookups are being consumed. If they nest includes across multiple domains, the SPF 10-lookup limitation can quickly become a production issue.
SPF is published as a TXT DNS entry. Even if you have only one SPF record, that DNS entry can trigger many DNS lookups behind the scenes. A flattened SPF record reduces that dependency by publishing optimized IP lists directly.
The SPF 10-lookup limitation is one of the most common SPF challenges for growing organizations. It affects SMB, Mid-Market, and enterprise environments, especially teams with multiple domains, MSPs managing client portfolios, or regulated industries such as Insurance and Financial Services.
A domain name may start with a simple SPF record, but as new platforms are added, each new DNS entry increases complexity. Marketing adds Mailchimp, sales adds Salesforce, IT adds Google Workspace, security adds IRONSCALES or Valimail-style controls, and finance adds a billing platform. Without structured SPF management, DNS lookups accumulate.
Mechanisms that can count toward the SPF 10-lookup limitation include:
include mechanisms
a mechanism references
mx mechanism references
redirect mechanism references
exists lookups
Some SPF macros and macro-based SPF configurations
Under RFC 7208, once SPF evaluation exceeds 10 DNS lookups, the result may be permerror. That failure can affect DMARC alignment, DMARC compliance, and policies such as a REJECT policy or QUARANTINE policy. In other words, SPF problems can become DMARC problems.
The phrase SPF 10-record limit is commonly used, but technically the issue is not the number of visible records. SPF permits only one SPF record per domain, published as a DNS entry. The actual constraint is 10 DNS lookups per SPF evaluation. Still, the SPF 10-record limit phrase is useful shorthand for explaining why complex SPF records fail.
An SPF flattening service automates the process of resolving vendor includes, extracting IP addresses, performing de-duplication, and generating a flattened SPF record. Instead of manually checking every service provider include, the SPF flattening service monitors changes and updates the DNS entry when vendors change their infrastructure.
This is where automated SPF flattening is especially valuable. Vendors frequently update IP ranges. If you manually flatten once and forget to maintain it, your SPF record may become stale. Dynamic SPF flattening with real-time rescanning reduces that risk by continuously checking the underlying records.
A typical SPF flattening service follows this workflow:
Scan the current SPF record.
Resolve all include mechanisms and nested vendor records.
Identify the full set of authorized senders.
Convert vendor references into optimized IP lists.
Apply de-duplication to remove overlapping IP addresses.
Generate a flattened SPF record.
Provide a DNS entry to copy, paste, and replace in your DNS provider.
Continue automatic flattening as vendors change.
For example, a tool such as AutoSPF flattener may monitor the SPF record, detect changes from Google Workspace or Mailchimp, and keep the flattened SPF record current. Some SPF management providers also support Cloudflare DNS integrations, API-based updates, team management, multiple domains, and alerting through dashboards.
Some environments rely on SPF macros or a macro-based SPF strategy to support complex routing. A capable SPF flattening service should understand when an SPF macro is safe to resolve and when it should preserve logic. Not every domain benefits from the same record optimization approach, especially when multiple mail servers, SMTP relays, or TLS-enabled outbound gateways are involved.
The strongest benefit of SPF flattening is improved email deliverability. When a receiving server can complete SPF evaluation without hitting the SPF 10-lookup limitation, legitimate mail is less likely to fail. That improves email authentication and reduces the chance of DMARC failures.
A flattened SPF record also lowers operational burden. Instead of editing a DNS entry every time a vendor changes, teams can rely on SPF management automation. This is especially useful for organizations with multiple domains, PCI domains, or brands managed by distributed IT and security teams.
Key advantages include:
Fewer DNS lookups during SPF authentication
Lower risk of permerror caused by the SPF 10-lookup limitation
Reduced manual SPF management and DNS entry changes
Better visibility into authorized senders
Improved DMARC compliance and DMARC alignment
Faster troubleshooting for email security incidents
Cleaner SPF record structure through de-duplication
Support for unlimited emails because SPF evaluation is DNS-based, not message-volume-based
Security-conscious buyers may also evaluate vendors for SOC-2 Type II, PCI DSS 4.0.1 support, Enterprise SSO, SAML, and uptime commitments such as 99.99% uptime. These requirements are common in Bizz, Financial Services, Insurance, and larger enterprise environments.
A reliable SPF flattening service reduces risk by ensuring the SPF record stays current while protecting against accidental overuse of DNS lookups. For MSPs, this can simplify SPF management across many client domains.
When choosing an SPF flattening service, focus on automation, accuracy, reliability, and ease of implementation. The best option should reduce setup time, simplify SPF management, and provide clear instructions to copy, paste, and replace the existing DNS entry.
Solutions in this space include AutoSPF, DuoCircle, Valimail, and tools referenced in communities such as G2 and DMARC Report. Some organizations compare these alongside broader email security platforms like IRONSCALES or an Email Security Gateway, depending on whether they need SPF-only optimization or a wider email security stack.
Evaluate an SPF flattening service based on:
Automated SPF flattening and dynamic SPF flattening
Real-time rescanning of service provider includes
Support for Cloudflare or Cloudflare DNS workflows
Clear visibility into DNS lookups and SPF compliance
Handling of SPF macros and macro-based SPF configurations
Teams management for distributed administrators
Support for multiple domains and delegated access
Strong uptime, ideally 99.99% uptime
Compliance posture, including SOC-2 Type II or PCI DSS 4.0.1 where relevant
Simple implementation with low setup time
The service should also explain exactly how it builds the flattened SPF record and how it reacts when IP addresses change. Good SPF management depends on transparency, not just automation.
Before replacing your SPF record, audit all email services and mail servers that send on behalf of your domain name. Confirm authorized senders, remove obsolete vendors, and review DMARC reporting to identify unknown sources. Then generate the flattened SPF record, publish the new DNS entry, and monitor SPF authentication results.
During implementation, avoid creating multiple SPF records. There should be one active SPF record per domain. If your DNS provider is Cloudflare, use the correct TXT record format and verify propagation. After publishing, check for the SPF 10-record limit risk by confirming that SPF evaluation remains under 10 DNS lookups.
The right SPF flattening service should make ongoing SPF management predictable: fewer DNS lookups, fewer manual changes, a cleaner flattened SPF record, and stronger email authentication across every sending platform.
