Summary
Emails frequently land in spam folders due to DMARC, SPF, and DKIM alignment failures, which occur when the domain in an email's From: header does not match the domain verified by either SPF or DKIM. DMARC serves as a policy layer that instructs recipient mail servers to quarantine or reject emails that fail this crucial alignment check, even if SPF or DKIM pass their basic authentication. This means for an email to be considered legitimate by DMARC, at least one of these protocols must not only authenticate the sender but also align its respective domain with the public From: domain.
Key findings
- DMARC Enforcement: DMARC explicitly instructs recipient servers to quarantine or reject emails if neither SPF nor DKIM aligns with the From: header domain, despite possibly passing individual authentication checks.
- SPF Alignment Specifics: SPF alignment fails when the Return-Path domain, often controlled by the Email Service Provider, does not match the From: header domain, leading to non-alignment unless specific configurations like a custom Return-Path are in place.
- DKIM Alignment Specifics: DKIM alignment fails when the domain specified in the DKIM signature's d= tag does not match the domain in the From: header of the email, even if the signature itself is valid.
- Combined Failure: If both SPF and DKIM fail to align with the From: header domain, DMARC's policy, particularly p=quarantine or p=reject, will be enforced, resulting in emails being routed to spam or blocked entirely.
- ESP Default Behavior: Many Email Service Providers do not align SPF or DKIM by default, which can cause deliverability issues when a sender implements an enforcing DMARC policy prematurely.
Key considerations
- Prioritize Alignment Fixes: To prevent DMARC failures, ensure the DKIM signing domain matches the From: domain, and configure a custom Return-Path with your ESP for SPF alignment. Aim to achieve alignment for both SPF and DKIM.
- Gradual DMARC Policy Implementation: If emails are going to spam due to a DMARC p=quarantine policy, consider reverting to p=none, monitoring mode, until all email sending streams are confirmed to be properly authenticated and aligned.
- Comprehensive Sending Control: Publishing DMARC records, especially with enforcing policies, requires tight control over all email sending sources to ensure valid and aligning SPF and DKIM across every mail stream.
- Monitor and Test: Before enforcing strict DMARC policies, rigorously monitor DMARC reports and test email deliverability from all sources to ensure proper alignment and avoid unintended spam classification.
What email marketers say
9 marketer opinions
DMARC's primary role in email deliverability is to ensure that the sender's apparent identity, as seen in the 'From:' header, is genuinely authenticated by either SPF or DKIM. Emails are often directed to spam when DMARC alignment fails, meaning the domain in the 'From:' address does not precisely match the domain validated by SPF's 'Return-Path' or DKIM's 'd=' tag. Even if SPF or DKIM individually pass their checks, DMARC will enforce its policy if this critical alignment is absent for both authentication methods, ultimately leading to messages being quarantined or rejected by recipient mail servers.
Key opinions
- DMARC's Core Requirement: DMARC requires either SPF or DKIM to not only pass authentication but also align their respective domains with the email's 'From' header domain.
- SPF Alignment Mechanics: SPF alignment fails when the 'Return-Path' domain, typically set by the sending service, does not match the 'From' header domain, preventing DMARC from validating the sender's identity through SPF.
- DKIM Alignment Mechanics: DKIM alignment fails when the domain specified in the DKIM signature's 'd=' tag does not match the 'From' header domain, despite the signature's technical validity.
- Consequence of Double Failure: When both SPF and DKIM fail to align with the 'From' domain, DMARC's specified policy-such as 'p=quarantine' or 'p=reject'-is enforced, commonly resulting in emails being moved to the junk folder or blocked.
- ESPs and Customization: Sending through an Email Service Provider without configuring a custom 'Return-Path' can prevent SPF from aligning, and using a different domain for DKIM signing than the 'From' domain can cause DKIM misalignment.
Key considerations
- Direct Alignment Fixes: To resolve DMARC alignment issues, ensure your DKIM signing domain precisely matches your 'From' domain, and configure a custom 'Return-Path' with your ESP for effective SPF alignment.
- Strategic DMARC Policy Deployment: Avoid immediate use of strict DMARC policies like 'p=quarantine' or 'p=reject' unless all email sending streams are verified to have proper SPF and DKIM authentication and alignment.
- Holistic Email Infrastructure Control: Successful DMARC implementation, especially with an enforcing policy, necessitates comprehensive control over all email sending sources to ensure consistent and aligned SPF and DKIM records across every outgoing mail stream.
- Continuous Monitoring and Testing: Regularly monitor DMARC reports and conduct thorough deliverability tests for all sending platforms to confirm alignment and prevent emails from being misclassified as spam.
Marketer view
Marketer from Email Geeks explains that when an email is sent from multiple domains that are not sufficiently similar, DMARC alignment fails. Specifically, if the 'From' address domain differs from the domain used for DKIM signing or in the Return-Path, DMARC will fail. In accordance with a DMARC policy set to p=quarantine, this failure results in the message being quarantined or placed in the junk folder.
6 Dec 2023 - Email Geeks
Marketer view
Marketer from Email Geeks explains that DMARC failing and emails going to spam can occur when DMARC is published with a p=quarantine policy without proper authentication in place. He notes that sending from a From: email address with one domain while DKIM signing with another domain leads to DKIM misalignment. Additionally, sending through an ESP without a custom return-path can prevent SPF from being effective. To resolve these issues for DMARC, it's necessary to fix either SPF or DKIM alignment, ideally both. A simple fix is to ensure the DKIM signing domain matches the From: domain. He also advises that publishing DMARC records requires tight control over email sending sources and ensuring valid, aligned SPF and DKIM across all mail streams to avoid problems, especially when using an enforcing DMARC policy.
9 Feb 2025 - Email Geeks
What the experts say
3 expert opinions
Emails are classified as spam or rejected due to DMARC alignment failures because DMARC policies explicitly instruct recipient servers to filter messages where the 'From:' domain does not align with either the SPF-authenticated domain or the DKIM-signed domain. This means that even if SPF or DKIM technically pass their authentication checks, DMARC will fail if the necessary domain alignment is missing. A common issue is that many Email Service Providers do not offer this alignment by default, leading to deliverability problems when senders prematurely implement strict DMARC policies like 'quarantine' or 'reject'.
Key opinions
- Policy Directives: DMARC policies, such as p=quarantine or p=reject, directly command Internet Service Providers to place emails that fail alignment into the spam folder or reject them entirely.
- Authentication vs. Alignment: An email can pass SPF or DKIM authentication individually but still fail DMARC if the authenticated domain does not align with the 'From:' header domain, which is a separate and crucial requirement.
- Dual Requirement: For an email to pass DMARC, at least one of SPF or DKIM must successfully authenticate AND have its domain align with the 'From:' domain.
- Immediate Consequences: When both SPF and DKIM fail to align with the 'From:' domain, the sender's DMARC policy is enforced, resulting in emails being quarantined in spam folders or completely rejected.
- ESP Default Gap: Many Email Service Providers do not configure SPF or DKIM for DMARC alignment by default, which can lead to deliverability issues when a strict DMARC policy is implemented without proper setup.
Key considerations
- Policy Reversion: If emails are being spammed due to a DMARC p=quarantine policy, it is advisable to temporarily revert to p=none, the monitoring mode, until all mail streams are fully authenticated and confirmed to be aligning correctly.
- Holistic Alignment Review: Before setting an enforcing DMARC policy, ensure that every single email sending source and platform you use is configured to pass both SPF and DKIM authentication with proper alignment to your 'From:' domain.
- Alignment Necessity: Understand that DMARC success hinges on domain alignment, not just basic SPF and DKIM authentication; simply having records is insufficient without the correct domain matches.
- Staged Policy Rollout: Avoid prematurely enforcing strict DMARC policies, as this will likely result in deliverability problems for emails from sources that are not yet DMARC-aligned.
Expert view
Expert from Email Geeks advises changing a DMARC policy from p=quarantine back to p=none until all mail streams are confirmed to be authenticated with aligning SPF and DKIM. She clarifies that when emails go to spam due to DMARC, it's because the sender's DMARC policy explicitly instructs Internet Service Providers (ISPs) to reject or spam emails that do not align. She highlights that DMARC implementers often fail to adequately explain that p=quarantine or p=reject policies will lead to unaligned emails being spammed, and that most emails from Email Service Providers (ESPs) do not align by default, thus causing deliverability issues if these policies are enforced prematurely.
6 Sep 2023 - Email Geeks
Expert view
Expert from Spam Resource explains that emails go to spam (or are rejected) when DMARC fails, which happens if SPF or DKIM pass authentication but fail alignment with the 'From:' domain. DMARC requires that at least one of SPF or DKIM both pass and align; otherwise, the receiving server will enforce the sender's DMARC policy, which can be 'quarantine' (spam folder) or 'reject'.
26 Jan 2022 - Spam Resource
What the documentation says
7 technical articles
Your emails often land in spam because DMARC (Domain-based Message Authentication, Reporting, and Conformance) specifically mandates that either SPF (Sender Policy Framework) or DKIM (DomainKeys Identified Mail) must not only authenticate your message but also align their respective domains with the 'From' header domain. When this critical alignment is absent for both authentication methods, DMARC considers the email unverified. This leads recipient mail servers to follow your DMARC policy, which typically instructs them to quarantine the message in spam folders or reject it outright, effectively preventing it from reaching the inbox.
Key findings
- DMARC Alignment Rule: DMARC failure signifies that the 'From' header domain, which recipients see, does not match the domain verified by either SPF's 'Return-Path' or DKIM's 'd=' tag, triggering its policy actions.
- SPF Domain Discrepancy: When the 'Return-Path' domain, used for SPF authentication, differs from the public 'From' header domain, SPF alignment fails under DMARC, potentially leading to spam if DKIM also fails alignment.
- DKIM Domain Mismatch: DKIM alignment fails when the domain in the DKIM signature's 'd=' tag does not precisely match the 'From' header domain, making the email unverified through DKIM for DMARC purposes.
- Dual Failure Impact: If both SPF and DKIM fail to achieve domain alignment, the DMARC policy (e.g., quarantine or reject) is enacted by receiving mail servers, directly causing emails to be delivered to spam folders or blocked.
- Universal Vendor Stance: Email service providers and security vendors universally affirm that DMARC uses domain alignment checks to determine the legitimacy of an email's 'From' address, preventing spoofing and ensuring deliverability based on policy.
Key considerations
- Alignment Modalities: Be aware that DMARC policies can be configured for either strict or relaxed alignment. Strict requires an exact match between domains, while relaxed allows for subdomain matches, impacting how SPF and DKIM failures are interpreted.
- Comprehensive Source Audit: It's crucial to identify every platform, service, and application that sends email on behalf of your domain to ensure each one is correctly configured for SPF and DKIM alignment, preventing unexpected DMARC failures.
- ESP Collaboration: Work closely with your Email Service Provider or other email sending vendors to ensure they support and correctly configure the necessary custom Return-Path settings for SPF alignment and DKIM signing domains.
- Phased Policy Rollout: To avoid immediate deliverability issues, implement your DMARC policy in stages-starting with p=none for monitoring, then p=quarantine for a period, before moving to p=reject, allowing time to address alignment problems.
Technical article
Documentation from Mimecast clarifies that DMARC alignment failure means neither SPF nor DKIM authentication has successfully aligned with the sender's 'From' header domain. DMARC requires at least one of these to pass for the email to be considered legitimate, otherwise, it may be sent to spam.
10 Dec 2024 - Mimecast
Technical article
Documentation from Google Workspace Admin Help states that DMARC failures occur when the domain in the 'From' header does not align with the domain authenticated by SPF or DKIM. If neither authentication method successfully aligns, DMARC considers the email unverified, leading to potential spam classification based on the domain's DMARC policy.
7 Mar 2022 - Google Workspace Admin Help
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