Summary
Rolling out DMARC enforcement effectively involves a phased approach that prioritizes proper DKIM and SPF setup before implementing more stringent DMARC policies. It's crucial to start with a 'p=none' policy to gather data, identify legitimate sending sources, and address any DKIM or SPF configuration issues. Understanding that forwarding breaks SPF/DKIM alignment, consider implementing ARC (Authenticated Received Chain) or SPF flattening to mitigate these issues. Monitor DMARC reports regularly to address configuration errors and ensure compliance, and gradually move to 'p=quarantine' and then 'p=reject' based on insights from the reports. Special attention should be given to DKIM signing for Google Workspace and third-party senders and utilizing tools like MXToolbox to check for record errors.
Key findings
- Phased Rollout: A phased implementation, starting with 'p=none', is crucial for data gathering and issue identification.
- DKIM/SPF Priority: Correct SPF and DKIM configurations are foundational before enforcing DMARC.
- Forwarding Impact: Forwarding breaks SPF/DKIM alignment, requiring strategies like ARC to mitigate DMARC failures.
- Reporting Importance: Regular DMARC report monitoring is essential for identifying errors and making informed policy changes.
- Third-Party Compliance: Ensuring third-party senders are properly authenticated is vital for DMARC enforcement.
Key considerations
- Initial Monitoring: Begin with 'p=none' to understand your email ecosystem and identify legitimate sending sources.
- DKIM Implementation: Carefully set up DKIM records, including key generation and DNS configuration, for all sending domains.
- Forwarding Strategies: Implement ARC or SPF flattening to manage forwarding-related DMARC failures effectively.
- Google Workspace: Ensure proper DKIM settings for Google Workspace, including custom signing domains, to prevent DMARC failures.
- Enforcement Gradualism: Move from 'p=none' to 'p=quarantine' and then 'p=reject' gradually, based on insights from DMARC reports.
- Third-Party Vetting: Verify that third-party senders are compliant with DMARC, with correct DKIM/SPF settings.
- Regular Auditing: Periodically review and adjust your DMARC policies based on ongoing monitoring and email ecosystem changes.
What email marketers say
15 marketer opinions
Rolling out DMARC enforcement requires a phased approach, starting with a monitoring policy (p=none) to gather data and identify legitimate email sources. Prioritize resolving DKIM issues by ensuring proper DKIM signing, particularly for Google Workspace and third-party senders. Implement ARC (Authenticated Received Chain) to mitigate forwarding-related DMARC failures. Use DMARC reporting tools to identify and correct configuration errors before gradually enforcing stricter policies (quarantine then reject).
Key opinions
- Phased Implementation: Begin with a monitoring policy (p=none) to collect data before enforcing stricter policies.
- DKIM Importance: Proper DKIM setup is crucial, especially for Google Workspace and third-party senders, to ensure email authentication.
- Forwarding Impact: Forwarding often breaks SPF and DKIM alignment, leading to DMARC failures; ARC can help mitigate this.
- DMARC Reporting: Using DMARC reporting tools helps identify configuration errors and unauthorized email sources.
Key considerations
- DKIM Configuration: Verify DKIM signing for all email sources, ensuring correct record setup and key usage.
- Forwarding Mitigation: Implement ARC or SPF flattening to handle forwarding scenarios effectively.
- Policy Transition: Gradually transition DMARC policies from 'p=none' to 'p=quarantine' and then 'p=reject', monitoring reports at each stage.
- Third-Party Senders: Ensure third-party senders comply with DMARC by including them in your SPF record or having them sign with DKIM.
- Error Checking: Use tools like MXToolbox to check for DMARC record errors before enforcement.
- Google Workspace Setup: Ensure custom DKIM signatures are properly set up for Google Workspace to avoid DMARC failures with Google Calendar invites.
Marketer view
Email marketer from Proofpoint advises that when dealing with DMARC enforcement, you must properly authenticate third-party senders, i.e., include them in your SPF record or have them sign with DKIM using your domain. They suggest working closely with these vendors to ensure they comply with DMARC requirements.
13 Mar 2024 - Proofpoint
Marketer view
Marketer from Email Geeks suggests that Google Calendar invites should not cause DMARC issues if Google Workspace DKIM is correctly implemented. SPF alignment may break because Google overwrites the Return-Path.
10 Oct 2021 - Email Geeks
What the experts say
2 expert opinions
Implementing DMARC should start with ensuring proper SPF and DKIM records are in place. Forwarding can cause DMARC failures due to SPF and DKIM mismatches. A staged deployment is recommended, beginning with a monitoring policy ('p=none') to assess impact and identify legitimate sending sources. Implementing ARC (Authenticated Received Chain) can help build trust and manage brand visibility.
Key opinions
- Forwarding Issues: Forwarding can cause DMARC failures due to SPF and DKIM record mismatches.
- Importance of SPF/DKIM: Proper SPF and DKIM setup is crucial before implementing DMARC.
- Staged Deployment: A staged deployment of DMARC is recommended, starting with a monitoring policy.
Key considerations
- ARC Implementation: Consider implementing ARC to help build trust and manage brand visibility, addressing forwarding issues.
- Monitoring Policy: Begin with 'p=none' to gather data and identify legitimate sending sources.
- SPF/DKIM Validation: Ensure SPF and DKIM records are correctly configured before enabling DMARC.
Expert view
Expert from Spam Resource explains the importance of proper SPF and DKIM setup prior to implementing a DMARC policy and suggests deploying DMARC in stages, starting with a monitoring policy (p=none) to assess the impact and identify legitimate sending sources before moving to quarantine or reject policies.
24 Sep 2022 - Spam Resource
Expert view
Expert from Word to the Wise explains that DMARC failures occur with forwarding because the original SPF and DKIM records don't match. She suggests implementing ARC (Authenticated Received Chain) and BIMI to build trust and manage brand visibility. Also, start with 'p=none' to gather data before enforcing stricter policies.
25 Mar 2025 - Word to the Wise
What the documentation says
4 technical articles
Rolling out DMARC enforcement involves setting up SPF and DKIM records, monitoring DMARC reports to identify legitimate email sources, and gradually increasing the DMARC policy from 'p=none' to 'p=quarantine' and then to 'p=reject'. To handle forwarding, use the Authentication-Results header and ARC (Authenticated Received Chain), which allows receiving servers to validate the authentication status of forwarded messages. Proper DKIM configuration is crucial, which includes generating DKIM keys, adding CNAME records to DNS settings, and enabling DKIM signing.
Key findings
- Progressive DMARC Policy: A gradual increase in DMARC policy, from 'p=none' to 'p=reject', minimizes disruptions.
- Forwarding Handling: Authentication-Results header and ARC help receiving servers validate forwarded messages.
- DKIM Configuration: Correctly configuring DKIM, including generating keys and adding CNAME records, is essential.
- Interoperability: DMARC is designed to work with SPF and DKIM to authenticate email, providing mechanisms for handling authentication failures.
Key considerations
- SPF and DKIM Setup: Start by ensuring SPF and DKIM are correctly configured before enabling DMARC.
- DMARC Report Monitoring: Regularly monitor DMARC reports to identify and address any authentication issues.
- ARC Implementation: Consider implementing ARC to improve the handling of forwarded emails.
- DNS Configuration: Pay close attention to DNS configuration, ensuring all necessary records are correctly set up.
Technical article
Documentation from Microsoft explains how to configure DKIM for your custom domain in Microsoft 365. This involves generating DKIM keys, adding CNAME records to your DNS settings, and enabling DKIM signing for your domain. Proper DKIM implementation ensures that your emails are authenticated and pass DMARC checks.
26 Sep 2024 - Microsoft
Technical article
Documentation from DMARC.org suggests using the Authentication-Results header and ARC (Authenticated Received Chain) to handle forwarded emails. These mechanisms allow receiving servers to validate the authentication status of forwarded messages, mitigating DMARC failures due to forwarding.
27 Sep 2022 - DMARC.org
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