An SPF PermError increases the chances of emails being marked as spam or rejected outright. Since DMARC treats an SPF PermError as a failure, emails with this error may be seen as untrustworthy. To avoid this risk, you must keep DNS-querying mechanisms and modifiers within the SPF record limited to 10 lookups.
Your DMARC’s SPF Record Checker can help you identify SPF configuration errors in your domain.
Why Is There an SPF Lookup Limit?
The SPF lookup limit exists to prevent threats like DDoS attacks and email spoofing. DNS lookups consume resources such as bandwidth, CPU, and memory. If the lookup count isn't controlled, it could lead to system overload, making servers vulnerable to abuse. The 10-lookup limit ensures a balance between security and efficiency.
How to Fix the “SPF Too Many DNS Lookups” Error?
Here are the most effective strategies to stay within the 10 DNS lookup limit while maintaining strong email authentication:
1. Remove Unnecessary “Include” Statements
The include mechanism redirects SPF validation to another domain’s SPF record, contributing to the DNS lookup count. If overused, it can easily exceed the limit.
✅ Solution: Eliminate redundant include statements. Only keep essential ones or replace them with IP-based mechanisms like ip4 or ip6.
2. Use ip4 and ip6 Mechanisms
The ip4 and ip6 mechanisms specify IP addresses directly in the SPF record without performing additional DNS lookups.
✅ Solution: Replace include statements with static IP addresses using ip4 and ip6. This reduces unnecessary DNS lookups.
3. Remove Duplicate Mechanisms from the Same Domain
Sometimes, domains refer back to each other unnecessarily in SPF records, leading to redundant DNS queries.
✅ Solution: Remove any repeated include mechanisms referring to the same domain multiple times.
4. Avoid the “ptr” Mechanism
The ptr mechanism performs reverse DNS lookups, which can generate multiple DNS queries per entry and are discouraged in modern SPF practices.
✅ Solution: Remove all ptr mechanisms from your SPF record.
5. Remove Unused or Invalid Domains
Expired or inactive domains included in your SPF record can contribute to the error.
✅ Solution: Double-check all included domains and remove any that are no longer in use or valid.
6. Use Flattened SPF Records
SPF record flattening involves replacing mechanisms with their resolved IP addresses, reducing DNS lookups significantly.
Steps to Flatten SPF Records:
- Query the DNS for each
includemechanism. - Collect all IP addresses returned.
- Replace the
includestatements with the IP addresses directly.
✅ Example Before Flattening:
plaintextCopyEditv=spf1 include:_spf.google.com include:mail.example.com -all
✅ Example After Flattening:
plaintextCopyEditv=spf1 ip4:192.168.1.1 ip4:192.168.1.2 -all
Pros:
- Reduces DNS lookups significantly.
Cons:
- Manual updates are required whenever the IP addresses change.
7. Use Your DMARC’s Dynamic SPF Management
An alternative to flattening is using Your DMARC’s SPF Optimization Tool, which dynamically manages SPF lookups without exceeding the 10-lookup limit.
✅ Benefits:
- Automatically handles SPF lookups.
- No need for manual flattening.
- Keeps records updated with IP changes.
Conclusion
Resolving the SPF PermError caused by excessive DNS lookups is essential for ensuring proper email deliverability and preventing security issues like spoofing. By optimizing your SPF record using the methods above—such as removing unnecessary include statements, using IP-based mechanisms, and dynamic SPF management with Your DMARC—you can maintain a secure and compliant email infrastructure.
For expert assistance in resolving complex SPF issues, try Your DMARC’s SPF Record Checker to streamline your email security setup today!
