Summary
Legitimate emails are often blocked when DMARC policy is set to 'quarantine' or 'reject' due to a variety of authentication failures. Common causes include misconfigured SPF or DKIM records, email forwarding practices that invalidate authentication, and the use of multiple sending platforms without proper alignment. Additionally, mailbox providers may apply local overrides, rogue sending activities can trigger blocks, and network issues or calendar invitations can lead to failures. Proper configuration, ongoing monitoring, and addressing forwarding issues are crucial for ensuring deliverability and avoiding unintentional blocking of legitimate mail.
Key findings
- Authentication Failure: SPF and DKIM misconfiguration or failures are the primary reason for legitimate emails being blocked.
- Forwarding Issues: Email forwarding frequently breaks SPF records, causing authentication to fail.
- Multiple Platforms: Using multiple email platforms without properly aligning SPF and DKIM records leads to DMARC failures.
- Reputation Matters: ISPs and MBPs can block emails based on sender reputation, even if DMARC passes.
- Policy Overrides: Mailbox providers can override DMARC policies, further impacting deliverability.
- Unintended Consequences: Legitimate use cases like calendar invites can trigger DMARC failures.
Key considerations
- Proper Configuration: Thoroughly configure and regularly update SPF and DKIM records.
- Forwarding Mitigation: Implement Sender Rewriting Scheme (SRS) or other solutions to handle forwarding.
- DMARC Alignment: Ensure all sending sources are aligned with the DMARC policy.
- Regular Monitoring: Continuously monitor DMARC reports to identify and address any authentication issues.
- Reputation Management: Proactively manage sender reputation to prevent blocks by ISPs and MBPs.
What email marketers say
16 marketer opinions
Legitimate emails are often blocked when DMARC policy is set higher than p=none due to a variety of reasons centered around authentication failures. These failures can arise from misconfigured SPF or DKIM records, email forwarding practices that invalidate these records, the use of multiple email sending platforms without proper alignment, and even network issues. Mailbox providers might also have local overrides that affect policy application. Rogue sending, calendar invitations, and third-party email services can also cause issues. Proper configuration and monitoring are crucial to avoid deliverability problems.
Key opinions
- Authentication Failures: Misconfigured SPF or DKIM records are a primary cause of legitimate emails failing DMARC checks.
- Email Forwarding: Forwarding often breaks SPF and DKIM, leading to authentication failures and blocking.
- Multiple Sending Platforms: Using multiple platforms without proper SPF/DKIM alignment increases the risk of DMARC failures.
- Network Issues: Network problems can cause authentication to fail, triggering DMARC policies.
- MBP Overrides: Mailbox providers might have local overrides impacting DMARC policy application.
- Rogue Sending: Unauthorized email sending can lead to DMARC failures if not properly authenticated.
- Calendar Invites: Calendar invitations, especially with non-Google Workspace, can trigger DMARC blocks.
- Third-Party Services: Improperly configured third-party email services contribute to DMARC failures.
Key considerations
- SPF/DKIM Configuration: Ensure SPF and DKIM records are correctly configured and up-to-date.
- Forwarding Solutions: Implement SRS or other solutions to manage forwarding-related authentication issues.
- Alignment: Align all email sending sources with your DMARC policy.
- Monitoring: Regularly monitor DMARC reports to identify and address issues.
- Reputation: Maintain a good sending reputation as mailbox providers anchor reputation to the authenticated identity.
Marketer view
Email marketer from EmailGeeks Community Forum user MailGuru responds to a question about DMARC issues, commenting that misconfiguration of email authentication protocols such as SPF and DKIM is a major cause. Also, use of multiple email sending services/servers is a high risk when you have a higher DMARC policy.
21 Jul 2024 - EmailGeeks Community Forum
Marketer view
Marketer from Email Geeks shares an edge case where using a free version of Google calendar with a custom email that’s not Google Workspace sometimes results in rejection notices due to DMARC policy, particularly with Microsoft recipients.
6 Jul 2024 - Email Geeks
What the experts say
4 expert opinions
Legitimate emails are blocked when DMARC policy is higher than p=none primarily due to authentication failures. These failures can be caused by spoofing, misconfigured SPF or DKIM, or issues like email forwarding which invalidate SPF records. Even if DMARC passes, mailbox providers might still block emails based on sender reputation. Addressing forwarding issues through SRS and ensuring proper SPF/DKIM alignment are crucial for deliverability.
Key opinions
- Authentication Failures: DMARC rejections are often due to authentication failures (SPF/DKIM) caused by spoofing or misconfiguration.
- Email Forwarding: Forwarding breaks SPF, causing legitimate emails to fail DMARC checks.
- MBP Identification: DMARC facilitates easier identification by ISPs/MBPs, impacting deliverability based on reputation.
Key considerations
- SPF/DKIM Configuration: Ensure SPF and DKIM are properly configured to avoid authentication failures.
- Forwarding Solutions: Implement SRS to handle forwarding-related SPF issues.
- Reputation Management: Maintain a positive sender reputation as ISPs/MBPs use authentication for identification.
Expert view
Expert from Email Geeks explains that DMARC failures causing rejections at p=reject are due to authentication failures. This can be caused by people spoofing your domain, misconfigured DKIM or SPF, or random issues like email forwarding that breaks DKIM signatures.
22 Nov 2021 - Email Geeks
Expert view
Expert from Word to the Wise explains that legitimate emails can be blocked under strict DMARC policies due to common issues such as email forwarding, where the forwarded email fails SPF checks because the sending server doesn't match the original domain's SPF record. Laura suggests implementing SRS (Sender Rewriting Scheme) to address forwarding issues.
19 Oct 2021 - Word to the Wise
What the documentation says
4 technical articles
DMARC policies, when set to higher levels than 'p=none', can block legitimate emails due to authentication failures stemming from forwarding, mailing list modifications, or misconfigured sending servers. Even without intentional spoofing, legitimate emails lacking proper SPF or DKIM authentication can be quarantined or rejected, as designed by the domain owner's policy, to protect against spoofing and phishing.
Key findings
- Authentication Failures: Legitimate emails fail DMARC checks due to SPF/DKIM authentication failures.
- Forwarding Issues: Email forwarding often breaks SPF/DKIM, causing authentication problems.
- Mailing List Modifications: Mailing list practices can alter emails, leading to authentication failures.
- Misconfigured Servers: Improperly configured sending servers contribute to authentication failures.
- Policy Enforcement: DMARC policies enforce quarantining or rejecting emails lacking authentication.
Key considerations
- SPF/DKIM Configuration: Ensure SPF and DKIM records are correctly configured to prevent authentication failures.
- Forwarding Solutions: Use DMARC-aware forwarding services or implement SRS to mitigate forwarding issues.
- Server Configuration: Properly configure sending servers to ensure correct authentication.
- Policy Review: Regularly review DMARC policy to balance security and deliverability.
Technical article
Documentation from DMARC.org notes that legitimate emails can be affected if they are forwarded in a way that breaks SPF or DKIM. This is often due to changes made by forwarding services that are not DMARC-aware, leading to authentication failures and subsequent blocking or spam filtering.
7 Apr 2025 - DMARC.org
Technical article
Documentation from RFC Editor explains that DMARC policy, when set to quarantine or reject, instructs receiving mail servers to handle messages that fail authentication based on the policy. This means legitimate emails lacking proper authentication can be quarantined or rejected, as intended by the domain owner's policy, to prevent spoofing and phishing attacks.
8 Jul 2024 - RFC Editor
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