Summary
Implementing a DMARC policy with p=reject is a crucial step for advanced email security, but it can sometimes inadvertently block legitimate emails, especially those sent via Google Workspace. This often happens because all sending sources for your domain, including Google Workspace itself and any third-party email service providers (ESPs), must be properly authenticated and aligned with your DMARC policy. The goal is to enforce a strong policy that protects against spoofing and phishing without disrupting your business communications.
Key findings
- Gradual approach: The safest way to implement p=reject is to start with a p=none policy and meticulously analyze DMARC reports. This allows you to identify all legitimate sending sources and fix any authentication issues before enforcing a stricter policy. Learn more about how to implement DMARC p=reject safely.
- Comprehensive authentication: Every service sending email on behalf of your domain, including Google Workspace and third-party ESPs, must have correctly configured SPF and DKIM records to achieve DMARC alignment.
- Subdomain inheritance: If your main domain has a p=reject policy, subdomains will inherit this policy unless they have their own explicit DMARC records. This can cause unexpected blocking for subdomain-sent emails if not properly managed.
- Dedicated DKIM for each sender: Google Workspace requires its own DKIM setup. This is separate from any DKIM records managed by a third-party ESP you might use for marketing emails. Google's support documentation provides a guide to turn on DKIM for your domain.
Key considerations
- Monitor DMARC reports: Regularly review DMARC aggregate and forensic reports. These reports are essential for identifying all legitimate sending sources and any authentication failures before tightening your policy. For assistance, consider utilizing DMARC monitoring solutions.
- DNS host capabilities: Verify if your DNS host supports 2048-bit DKIM keys. If not, you may need to use a 1024-bit key, although 2048-bit keys are generally preferred for stronger security.
- Education is crucial: Ensure you fully understand how DMARC works and why emails might be failing authentication before making any changes. Blind implementation can lead to significant deliverability issues.
- Avoid blind implementation: Do not implement p=reject without thoroughly understanding its implications and verifying all legitimate email sending sources.
What email marketers say
Email marketers are often on the front lines of DMARC implementation, balancing the desire for robust email security with the practical need to ensure their campaigns and transactional emails reach the inbox. Many have experienced the pitfalls of premature DMARC enforcement, particularly when multiple sending systems like Google Workspace are involved.
Key opinions
- Proactive policy setting: Some marketers set DMARC to p=reject early on, believing it to be the best practice for compliance, only to discover legitimate Google Workspace emails are subsequently blocked. This highlights the importance of a phased approach to DMARC enforcement.
- CNAME record reliance: Marketers frequently manage SPF and DKIM via CNAME records provided by their bulk ESPs (e.g., SendGrid). However, they might overlook that Google Workspace requires its own separate DKIM setup, leading to authentication failures for internal emails.
- Report analysis is key: There's a strong consensus that reviewing DMARC reports is critical for identifying and resolving authentication issues. Without this, pinpointing why emails are being blocked becomes a guessing game.
- Client education challenge: Educating less tech-savvy clients on the necessity of configuring DKIM for all their sending platforms, including Google Workspace, can be a significant hurdle for marketers and agencies.
Key considerations
- Verify all sending platforms: Ensure that every platform sending email on behalf of your domain has correctly configured SPF and DKIM. This includes Google Workspace for internal emails and any other services for marketing or transactional emails. Email on Acid provides insights on what DMARC policy senders should use in 2025.
- Understand domain scope: Be aware if the DMARC p=reject policy applies to the organizational domain or a subdomain, as this directly affects inheritance and potential blocking.
- Phased rollout: Adopt a phased approach for DMARC enforcement, moving from p=none to p=quarantine and then p=reject only after verifying all legitimate traffic. For ESP-specific guidance, see our article on DMARC p=reject with ESPs.
- User education: Proactively educate clients or internal teams on the importance of DMARC and proper email authentication to prevent issues before they arise.
Marketer view
Marketer from Email Geeks suggests starting DMARC implementation with p=none, then fixing any authentication issues that surface. Only after resolving these should you consider moving to a quarantine or reject policy. This iterative approach helps prevent unintended email blocking.
Marketer view
Marketer from Email Geeks notes that if you are managing a customer's DKIM/SPF via CNAME records for a bulk sender, you need to be aware of other authentication aspects they might control, especially for their main organizational domain. It's crucial to ensure all sending sources are covered.
What the experts say
Email deliverability experts consistently advocate for a methodical and data-driven approach to DMARC implementation. They stress that rushing to a p=reject policy without proper authentication for all sending streams, particularly for services like Google Workspace, is a recipe for deliverability disaster.
Key opinions
- Prioritize authentication fixes: Experts strongly advise starting with p=none to identify and fix authentication issues before moving to quarantine or reject. This phased implementation is crucial for avoiding legitimate email blocking. For more details, see our article on simple DMARC examples.
- Review reports thoroughly: It is not enough to simply set up DMARC. Experts emphasize the need to properly review DMARC reports to understand all traffic, identify what's broken, and ensure all legitimate mail is authenticated correctly. Consider using a DMARC monitoring service for comprehensive insights.
- DKIM for all senders: A common point of failure is neglecting to implement DKIM for every email sender, including Google Workspace and any other ESPs or CRMs. DKIM needs to be set up for each specific sending platform.
- Understanding over blind action: Experts stress the importance of understanding DMARC, SPF, and DKIM thoroughly rather than implementing changes blindly. This education prevents misconfigurations and subsequent deliverability issues.
Key considerations
- Gradual enforcement: Transition to stricter policies like p=quarantine or p=reject only after you have confirmed that all your legitimate mail streams consistently align with SPF or DKIM. Our guide on safely transitioning your DMARC policy offers a detailed roadmap.
- Diagnostic tools: Utilize robust tools that provide clear insights into your email authentication status. This helps in quickly diagnosing and resolving DMARC, SPF, or DKIM failures. Spamresource.com offers insights into compliance for major providers.
- Identify all sending services: Create a comprehensive inventory of every service that sends email on behalf of your domain. This ensures no legitimate source is missed during the authentication setup, which is crucial for full DMARC compliance.
- Subdomain DMARC records: If your organizational domain is at reject, consider creating explicit DMARC records for subdomains, especially if they send mail, to prevent unintended policy inheritance and blocking.
Expert view
Expert from Email Geeks strongly advises starting DMARC implementation with p=none to correctly fix all authentication issues before considering a move to quarantine or reject. This phased approach helps prevent accidental blocking of legitimate emails.
Expert view
Expert from Email Geeks emphasizes the need for proper review of DMARC reports. They state that guessing what's broken is unproductive and users should understand DMARC and then fix what is actually wrong, advocating for more education in the process.
What the documentation says
Official documentation from major email providers and industry standards bodies provides critical guidance on DMARC implementation. It consistently emphasizes the need for careful configuration of SPF and DKIM for all email streams to ensure DMARC alignment and prevent legitimate emails from being blocked, especially with a p=reject policy.
Key findings
- DMARC policy application: A DMARC policy published in DNS instructs receiving mail servers on how to handle emails that fail DMARC authentication, providing options like none, quarantine, or reject. Our guide provides a list of DMARC tags and their meanings.
- DKIM for Google Workspace: Google Workspace documentation explicitly details the steps to enable DKIM for your domain. This process is crucial for protecting against spoofing and phishing, and to ensure that emails sent from Google Workspace are delivered reliably. The Google Workspace Admin Help site explains how to turn on DKIM for your domain.
- Dependency on SPF and DKIM: DMARC functionality relies heavily on the correct implementation and alignment of both SPF and DKIM records. If either of these fails to authenticate and align, DMARC will fail. Our simple guide to DMARC, SPF, and DKIM provides a foundational understanding.
- Bulk sender requirements: Recent updates from Google and Yahoo mandate DMARC implementation for bulk senders, with a minimum policy of p=none alongside proper SPF and DKIM configuration to ensure email deliverability.
Key considerations
- DNS record publication: DMARC policies are activated by publishing a DMARC record as a TXT record in your domain's DNS. Incorrect or missing DNS entries can prevent your policy from being enforced.
- Email routing rules: Google Workspace provides email routing rules and third-party governance tools that can be used to ensure only authorized senders are using your domain. This proactive measure helps in maintaining a strict DMARC policy without blocking legitimate emails. Patronum.io discusses how Microsoft's new DMARC enforcement means for Google Workspace admins.
- Domain alignment: For DMARC to pass, the domain in the From header (RFC5322.From) must align with the domain authenticated by SPF (Return-Path) or DKIM (d= tag).
- Monitoring and adjustment: Documentation consistently advises continuous monitoring of DMARC reports (aggregate and forensic) to ensure ongoing compliance and to quickly troubleshoot any emerging issues. Learn more about understanding and troubleshooting DMARC reports.
Technical article
Documentation from Esecurityplanet.com explains that to set up DMARC, organizations must publish a text file, known as a DMARC record, with their DNS registrars. This record defines the policy for handling unauthenticated emails.
Technical article
Documentation from Fortinet defines DMARC as a protocol requiring DKIM or SPF to be in place on an email domain, along with a published DMARC record in the DNS. The DMARC policy process helps in email authentication and combating spoofing.
Related resources
14 resources
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