Summary
SPF flattening aims to mitigate DNS lookup limits, but it may not be universally compatible with email evaluation tools due to issues with macro handling and complex records. Experts and marketers recommend DKIM and DMARC as alternatives for robust authentication, as they don't rely on DNS lookups in the same way as SPF. Managing includes, segmenting sending domains, and regularly validating and updating SPF records are crucial. Comprehensive testing with multiple tools and continuous monitoring of deliverability metrics are also essential for maintaining email deliverability.
Key findings
- Tool Compatibility Issues: Some email evaluation tools struggle with SPF macros, flatteners, and complex records, leading to false positives and inaccurate results.
- DNS Lookup Limits Impact: SPF records are subject to DNS lookup limits; exceeding these limits causes authentication failures and negatively impacts deliverability.
- DKIM/DMARC as Alternatives: DKIM and DMARC provide reliable alternatives to SPF, offering authentication methods that don't rely on DNS lookups and enhance overall email security.
- Importance of Record Management: Careful management of SPF records, including limiting includes and regularly evaluating entries, is essential for avoiding DNS lookup issues.
Key considerations
- Evaluate Flattening Necessity: Assess whether SPF flattening is truly necessary, as too many unnecessary elements in the SPF record can create problems.
- Regular Record Validation: Routinely validate SPF records and monitor deliverability metrics to verify their accuracy and effectiveness in preventing deliverability issues.
- Implement Multi-Tool Testing: Use multiple reputable testing tools and/or manual verification methods to ensure accurate SPF record configuration.
- Monitor DNS Propagation: Be aware that SPF flattening may cause temporary deliverability issues due to DNS propagation delays, and monitor DMARC reports for insights.
- Keep Records Updated: If SPF flattening is used, keep the flattened record updated whenever any included IP ranges are changed to avoid authentication failures.
What email marketers say
10 marketer opinions
SPF flattening aims to resolve DNS lookup limitations in SPF records, but it doesn't guarantee universal compatibility with email evaluation tools. Alternatives like DKIM offer authentication without DNS lookups. Regular SPF record validation, deliverability monitoring, and multi-tool testing are essential. Managing SPF includes, segmenting sending domains, and promptly updating records after changes are also key.
Key opinions
- DNS Lookup Limits: SPF flattening helps address DNS lookup limits, which can cause authentication failures if exceeded.
- Tool Incompatibilities: Some email evaluation tools struggle with complex SPF records or macros, leading to inaccurate results.
- DKIM Alternative: DKIM offers a reliable alternative to SPF, providing authentication without relying on DNS lookups.
- Comprehensive Testing: Using multiple testing tools and manual verification helps ensure SPF records are accurate.
Key considerations
- Monitor Changes: Monitor SPF records and deliverability metrics after implementing flattening, as DNS propagation delays can cause temporary issues.
- Record Updates: If flattening is used, keep the flattened record updated whenever any included IP ranges are changed.
- Managed Includes: Avoid too many includes in the SPF record to minimize DNS lookup limits. Consider segmenting sending domains to distribute the SPF load.
- Use Alternative Tools: Comprehensive deliverability testing tools provide insight into how different email providers handle the email, which can help mitigate SPF and evaluation issues.
- Regular Validation: Routinely validate SPF records to ensure accuracy and effectiveness in preventing deliverability problems.
Marketer view
Email marketer from NeilPatel.com shares that SPF records should be optimized to avoid exceeding the DNS lookup limit. While flattening can help, carefully managing included domains and services is crucial to prevent deliverability issues, especially when using evaluation tools that may not handle complex SPF records well.
25 Feb 2022 - NeilPatel.com
Marketer view
Email marketer from ZeroBounce points out the need to regularly validate SPF records. They further recommend monitoring deliverability metrics after any changes to SPF, including flattening, to verify effectiveness.
12 May 2023 - ZeroBounce
What the experts say
6 expert opinions
SPF flattening can negatively impact email evaluation tools because some tools don't handle SPF macros, flatteners, or automation well, leading to inaccurate results. A key finding is that SPF records have limitations, like DNS lookup limits. Alternatives to flattening include using DKIM (which doesn't rely on DNS lookups) and carefully managing includes within the SPF record. Considerations include evaluating whether SPF flattening is truly necessary and managing SPF records carefully to avoid DNS lookup issues. It's recommended to test SPF records using multiple tools or manual verification.
Key opinions
- Tool Limitations: Some email evaluation tools struggle with SPF macros, flatteners, and automation, resulting in inaccurate assessments.
- DNS Lookup Limits: SPF records have limitations, including a maximum number of DNS lookups; exceeding these limits causes authentication failures.
- DKIM Alternative: DKIM offers an alternative authentication method that doesn't rely on DNS lookups.
Key considerations
- Need for Flattening: Evaluate the actual need for SPF flattening; too many unnecessary elements might be included in the SPF record.
- Careful Management: Carefully manage SPF records to avoid DNS lookup issues by limiting includes and regularly evaluating and cleaning up entries.
- Multiple Tests: Test SPF records using multiple evaluation tools and/or manual verification to ensure accuracy.
Expert view
Expert from Email Geeks shares that some checkers have trouble with macros and flatteners and automation in the SPF record. He suggests testing at Gmail and using the Kitterman SPF record checker.
10 Sep 2023 - Email Geeks
Expert view
Expert from Email Geeks explains that SPF macros are not handled well by some tools. His checker at tools.wordtothewise.com fails horribly on them.
18 Feb 2024 - Email Geeks
What the documentation says
5 technical articles
SPF implementations have limitations in processing macros and complex SPF records, causing evaluation errors by some tools. While flattening aims to reduce complexity, alternatives like DKIM and DMARC are recommended for robust email authentication, as DKIM isn't subject to the same DNS lookup limitations as SPF. Testing with multiple tools and monitoring deliverability are essential for proper configuration.
Key findings
- Processing Limitations: SPF implementations struggle with macros and complex SPF records.
- DKIM/DMARC: DKIM and DMARC offer robust email authentication alternatives, with DKIM not being subject to DNS lookup limits like SPF.
- Evaluation Errors: Evaluation tools may misinterpret macros and SPF syntax, leading to false positives.
Key considerations
- Multiple Testing: Test SPF records using multiple reputable tools to mitigate evaluation errors.
- Deliverability Monitoring: Monitor email deliverability to ensure proper configuration and identify potential issues.
- SPF Sufficiency: SPF alone may not be sufficient; implement DKIM alongside SPF and align them using DMARC.
- Best Practices: Adhere to SPF best practices, including limiting the number of DNS lookups and monitoring SPF records for changes.
Technical article
Documentation from Microsoft explains SPF best practices, including limiting the number of DNS lookups. They recommend using alternatives like DKIM and DMARC and monitoring SPF records for changes in included services.
8 Jan 2024 - Microsoft Learn
Technical article
Documentation from Google explains that some evaluation tools may not fully support all SPF syntax or macro expansions, which could lead to false positives. It is recommended to test SPF records using multiple reputable tools and to monitor email deliverability to ensure proper configuration.
4 Sep 2024 - Google Workspace Admin Help
Can a sender modify SPF records to alter SPF checking behavior?
How can I optimize my SPF record to stay within the lookup limit when using multiple email sending services?
How complex is the SPF spec for building an SPF checking library?
How do I fix the MXtoolbox SPF record DNS lookup limit exceeded error?
What are the best practices for using SPF flatteners and managing SPF records?
When is SPF flattening necessary for email authentication?
