Summary
The overwhelming consensus is that SPF hardfail should generally *not* be enforced if DMARC is properly implemented. DMARC, building upon SPF and DKIM, acts as a policy layer that dictates how receiving mail servers should handle messages. If DMARC passes (due to either SPF or DKIM alignment), the specific SPF result becomes less important, and the DMARC policy takes precedence. Major mailbox providers (MBPs) typically defer to DMARC in such cases. DMARC alignment protects domains from unauthorized use and spoofing, giving domain owners control over message handling.
Key findings
- DMARC Takes Precedence: DMARC overrides SPF when properly configured and passing authentication.
- Policy Layer: DMARC acts as a policy layer, allowing domain owners to define how email receivers should handle authentication failures.
- Alignment is Key: DMARC relies on alignment with either SPF or DKIM; at least one must pass for DMARC to be effective.
- MBP Behavior: Major Mailbox Providers (MBPs) typically defer to DMARC and do not enforce SPF hardfail when DMARC passes.
- Protection Against Spoofing: DMARC provides protection against domain spoofing and unauthorized use.
Key considerations
- DMARC Configuration: Properly configure DMARC and ensure alignment with SPF and/or DKIM.
- Monitoring: Monitor DMARC reports to identify authentication issues and potential abuse.
- Transition: Gradually transition to a stricter DMARC policy (from 'none' to 'quarantine' to 'reject') to minimize potential disruptions.
- SPF still important: SPF is still important when DMARC is not in place
What email marketers say
12 marketer opinions
The consensus among email marketers and documentation suggests that when DMARC is properly implemented and passes authentication (either through SPF or DKIM alignment), the enforcement of SPF hardfail becomes less critical or even irrelevant. DMARC acts as a policy layer that overrides SPF results, dictating how receiving servers should handle messages based on alignment with SPF or DKIM. Major mail providers typically prioritize DMARC, using it to determine if a message is legitimate, even if SPF fails. Domain owners can define these policies within their DMARC records.
Key opinions
- DMARC Overrides SPF: DMARC is designed to take precedence over SPF. If a message passes DMARC due to either SPF or DKIM alignment, the SPF result is less important.
- DMARC as Policy Layer: DMARC functions as a policy layer, allowing domain owners to instruct receiving mail servers on how to handle messages failing authentication.
- Industry Practice: Major Mailbox Providers (MBPs) generally do not enforce SPF hardfail when DMARC is in place, using DMARC as the primary indicator of legitimacy.
- SPF Hardfail Still Relevant: SPF Hardfail is still a factor when DMARC is not in place.
Key considerations
- DMARC Configuration: Ensure DMARC is properly configured and aligned with either SPF or DKIM to take advantage of its policy enforcement capabilities.
- SPF and DKIM Alignment: Understand that DMARC relies on alignment with either SPF or DKIM. Both authentication methods should be properly set up to support DMARC.
- Monitoring DMARC Reports: Regularly monitor DMARC reports to identify and address any authentication issues or potential spoofing attempts.
- Hardfail Record: A record of v=spf1 -all means that a DMARC pass will not override SPF failing.
Marketer view
Email marketer from Postmark explains that the purpose of DMARC is for recipients to check the SPF and DKIM records, and if it fails, it will follow the DMARC policy. If it passes, then other failures are irrelevant.
2 Feb 2025 - Postmark
Marketer view
Email marketer from MXToolbox shares that DMARC allows domain owners to specify how email receivers should handle messages that fail authentication checks (SPF and DKIM). If the message passes DMARC because one authentication method aligns, hard fail is irrelevant.
18 Feb 2025 - MXToolbox
What the experts say
1 expert opinions
An expert from Word to the Wise highlights that DMARC alignment is crucial for safeguarding domains against unauthorized usage and spoofing attempts by malicious actors. DMARC policies enable domain owners to instruct mail receivers on how to handle messages that fail authentication, providing various options such as taking no action, quarantining, or rejecting the messages. This mechanism plays a vital role in securing email communications.
Key opinions
- DMARC Protects Domains: DMARC alignment is essential for protecting domains from unauthorized use and spoofing by bad actors.
- DMARC Policy Enforcement: DMARC policies allow domain owners to specify how email receivers should handle messages that fail authentication, offering choices from no action to quarantining or rejecting messages.
- Key to Secure Communications: DMARC is key to securing email communications.
Key considerations
- Implement DMARC: Organizations should implement DMARC to protect their domains.
- Define DMARC Policy: Organizations must define their DMARC policies regarding handling of authentication failures.
- Email Security: Organizations must prioritize email security through mechanisms like DMARC.
Expert view
Expert from Word to the Wise states that DMARC alignment allows domains to protect themselves from unauthorized use and spoofing by bad actors. A DMARC policy informs mail receivers what to do with messages that fail authentication, offering choices from no action to quarantining or rejecting the messages. This is key for securing email communications.
23 Jul 2024 - Word to the Wise
What the documentation says
3 technical articles
According to documentation from Google, DMARC.org, and Microsoft, DMARC takes precedence over SPF. If an email fails SPF but passes DMARC, the DMARC policy determines how the email is handled. DMARC builds upon SPF and DKIM, acting as a policy layer, and if DMARC passes (due to either SPF or DKIM alignment), the SPF result becomes less important. DMARC uses the results of SPF and DKIM to determine if a message is legitimate; if DMARC validation passes, the mail is treated as genuine even if SPF fails, as long as DKIM passes and aligns or vice versa.
Key findings
- DMARC Precedence: If an email fails SPF but passes DMARC, the DMARC result takes precedence.
- DMARC as Policy: DMARC acts as a policy layer built upon SPF and DKIM.
- SPF Less Important: If DMARC passes (due to either SPF or DKIM alignment), the specific SPF result is less important.
- DMARC for Legitimacy: DMARC uses SPF and DKIM to determine if a message is legitimate.
Key considerations
- Configure DMARC: Ensure DMARC is configured correctly to handle emails based on the organization's policy.
- Implement SPF and DKIM: Implement both SPF and DKIM for comprehensive email authentication.
- Monitor DMARC Reports: Monitor DMARC reports to identify and address any authentication issues or potential security threats.
Technical article
Documentation from Microsoft explains that DMARC uses the results of SPF and DKIM to determine whether a message is legitimate. If DMARC validation passes, the mail is treated as genuine even if SPF fails, as long as DKIM passes and aligns or vice-versa.
4 Jul 2024 - Microsoft
Technical article
Documentation from DMARC.org explains that DMARC builds upon SPF and DKIM, acting as a policy layer. If DMARC passes (due to either SPF or DKIM alignment), the specific SPF result is less important.
6 May 2022 - DMARC.org
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