Summary
Troubleshooting and fixing SPF and DMARC for email deliverability involves a multifaceted approach. Experts recommend considering specialized DMARC companies for setup and emphasize the importance of proper SPF record configuration, including adherence to the 10 DNS lookup limit. DMARC deployment should be phased, starting with a monitoring policy ('p=none') before transitioning to stricter enforcement. Key considerations include validating SPF/DKIM alignment with the 'From:' domain, monitoring DMARC reports for authentication issues, using testing tools, and consolidating multiple SPF records. Special attention should be given to situations where only DKIM alignment is present, as failures can occur. Also, consider using subdomains for different email types to isolate deliverability issues, and be wary of DMARC solutions that seem too cheap or quick, with Microsoft issues and Mailchimp changes being known to cause issues. Overall a continued, phased approach is required.
Key findings
- DMARC Expertise: Specialized DMARC companies can simplify setup with purpose-built tools.
- SPF Configuration: Valid SPF records require correct formatting, root domain publication, all sending sources, and adherence to DNS lookup limit.
- DMARC Staged Rollout: DMARC deployment should follow 'p=none' -> 'p=quarantine' -> 'p=reject' for safe implementation.
- Mailchimp and SPF/DKIM: Mailchimp requires using the 2 DKIM CNAME records, but doesn't need the traditional SPF include.
- DKIM Alignment Risk: Reliance on DKIM alone poses risks as failures can cause DMARC validation to fail.
- Ongoing DMARC Vendor Costs: A DMARC vendor can be expected to be an ongoing cost, and if it's too low there may be problems
Key considerations
- SPF Record Review: Review Sendgrid and ensure the include is needed, also remove unused items like 'mx'.
- Monitor Reports: Monitor DMARC reports proactively to identify authentication gaps and potential threats.
- Validation with tools: Validate settings using testing tools to simulate mail flow and catch misconfigurations.
- Correct errors: Address syntax errors or exceeding SPF DNS lookup limits promptly.
- Subdomain Separation: Utilize subdomains to isolate deliverability issues between email types.
- Authentication Alignment: If SPF fails, ensure DKIM passes AND is aligned with the from domain.
- Avoid multiple records: Consolidate and prevent having multiple SPF records.
What email marketers say
15 marketer opinions
Troubleshooting and fixing SPF and DMARC settings for email deliverability involves several key areas. Correct SPF configuration is crucial, including ensuring a single SPF record, staying within the 10 DNS lookup limit, and accurately listing all sending sources. DMARC implementation should be phased, starting with monitoring before enforcing policies. Email authentication issues can stem from forwarding, incorrect syntax, and misalignment between SPF/DKIM and the 'From:' domain. Monitoring DMARC reports, using testing tools, and consolidating SPF records are all important for maintaining deliverability. Also, consider using subdomains for different email types and understanding that less expensive DMARC deployment options might not be sufficient.
Key opinions
- SPF Configuration: Proper SPF configuration is crucial, involving single record, staying within 10 DNS lookups and accurate source listing.
- DMARC Phased Implementation: DMARC should be implemented in phases (none -> quarantine -> reject) to avoid blocking legitimate email.
- Authentication Alignment: Either SPF or DKIM must align with the 'From:' domain for DMARC to pass, and both have to validate. Forwarding can cause SPF failures.
- Mailchimp SPF record changes: Old Mailchimp accounts required SPF record, but they have now moved to DKIM for authentication
- Troubleshooting considerations for DMARC vendors: DMARC deployment should be considered ongoing, it should be expected to take months or even a year for full deployment and to reach the reject mode.
Key considerations
- Monitoring and Reporting: Regularly monitor DMARC reports to identify and address authentication issues and potential abuse.
- Testing Tools: Utilize email testing tools to validate SPF and DMARC configurations before and after making changes.
- Consolidation: Consolidate multiple SPF records into a single record to avoid authentication failures.
- Subdomain Usage: Consider using subdomains to isolate deliverability issues and simplify SPF and DMARC management for different email types.
- DMARC Deployment Costs: DMARC deployment should take months and if a DMARC deployment is promised in less than 6 months or costs less than $20,000, it's likely not a genuine service.
Marketer view
Email marketer from AuthSMTP explains that having multiple SPF records can invalidate SPF authentication. You should consolidate all SPF records into a single record.
2 Aug 2021 - AuthSMTP
Marketer view
Email marketer from Mailjet shares that DMARC implementation should be done in stages: starting with a 'p=none' policy to monitor reports, then moving to 'p=quarantine' and finally 'p=reject' as you gain confidence in your authentication setup.
7 Sep 2022 - Mailjet
What the experts say
5 expert opinions
Troubleshooting SPF and DMARC involves careful setup and monitoring. DMARC setup is often best handled by specialized DMARC companies. If there is no DMARC record then there is nothing to fix. Multiple SPF records is bad but the correct setup depends on where mail is sent from. It is important to note that authentication can fail with only DKIM alignment. Start DMARC enforcement with a 'p=none' policy before moving to stricter policies to monitor traffic. Finally, avoid exceeding the 10 DNS lookup limit in SPF records by flattening them.
Key opinions
- DMARC Expertise: Specialized DMARC companies often provide superior tools and expertise for DMARC setup.
- DMARC Initial Policy: Begin DMARC enforcement with a 'p=none' policy to monitor traffic and identify legitimate sending sources.
- SPF DNS Lookup Limit: Exceeding the 10 DNS lookup limit in SPF records can cause authentication failures; flatten records to avoid this.
- No action with no DMARC record: If there is no DMARC record then there is nothing to fix.
- DKIM Alignment Failure: Authentication can fail with only DKIM alignment, highlighting the importance of both SPF and DKIM validation.
Key considerations
- SPF Setup Location: When setting up SPF record it depends on where the mail is sent from.
- DMARC Implementation: Gradually increase the DMARC policy (p=none -> p=quarantine -> p=reject) to minimize the risk of blocking legitimate emails.
- Troubleshooting Providers: Advised being cautious with providers lacking DKIM authentication, and mentions ARC specifications will work better with indirect mail flows as policy is enforced.
- Microsoft and DKIM: There have been issues with Microsoft and DKIM that can cause DMARC checks to fail.
Expert view
Expert from Spam Resource explains that when troubleshooting DMARC, start with a policy of 'p=none' to monitor traffic and identify legitimate sending sources before gradually increasing the policy to 'p=quarantine' or 'p=reject.' This approach minimizes the risk of blocking legitimate emails and allows for thorough testing.
15 Aug 2023 - Spam Resource
Expert view
Expert from Email Geeks explains there's nothing to 'fix' if DMARC record isn't published and multiple SPF records are bad, the correct ones depend on where mail is sent from.
26 Dec 2024 - Email Geeks
What the documentation says
5 technical articles
Troubleshooting SPF and DMARC involves ensuring correct formatting, publishing records at the root domain, including all sending sources, staying within the DNS lookup limit, and applying correct DMARC policies. A crucial aspect is regular monitoring of DMARC aggregate and forensic reports to identify authentication issues, potential abuse, and misconfigured sending sources. Message headers should be reviewed to understand authentication results, and DNS records must be verified. Analyzing DMARC failure reports can highlight specific issues like SPF softfails or DKIM problems, which require XML data analysis.
Key findings
- SPF Setup: SPF records must be correctly formatted, published at the root domain, include all sending sources, and adhere to the 10 DNS lookup limit.
- DMARC Errors: Common DMARC errors include syntax issues, incorrect policy application, and failure to monitor reports.
- Authentication Analysis: Message headers provide insights into authentication results, crucial for diagnosing SPF and DMARC issues.
- DMARC Reporting: Regular monitoring of DMARC reports identifies authentication issues, abuse, and misconfigurations.
- Failure Report Analysis: DMARC failure reports can pinpoint issues like SPF softfails or DKIM problems via XML data.
Key considerations
- Record Correction: Fixing syntax errors and ensuring correct formatting in SPF and DMARC records is critical.
- Policy Application: Applying the correct DMARC policy based on the organization's risk tolerance and authentication setup.
- Ongoing Monitoring: Continuously monitoring DMARC reports to adapt and refine SPF and DMARC policies.
- DNS Verification: Regularly verifying that DNS records are correctly configured to prevent authentication failures.
- XML Analysis: Understanding and analyzing XML data within DMARC failure reports to diagnose specific authentication problems.
Technical article
Documentation from Valimail explains that DMARC failure reports can highlight specific authentication issues such as SPF softfails or DKIM signature problems. Understanding these reports requires analyzing the XML data for clues about the reasons for failure.
14 Nov 2024 - Valimail
Technical article
Documentation from Microsoft shares a guide on identifying if SPF or DMARC are causing email delivery issues, suggesting reviewing the message headers for authentication results and verifying the DNS records are correctly configured.
20 Sep 2023 - Microsoft
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