How do DMARC quarantine and reject policies affect sender reputation and email delivery?
Michael Ko
Co-founder & CEO, Suped
Published 24 May 2025
Updated 16 Aug 2025
9 min read
Implementing DMARC policies is a critical step for protecting your domain from email spoofing and phishing attacks. While DMARC is essential, understanding the nuances of its enforcement policies, specifically p=quarantine and p=reject, is vital for maintaining strong sender reputation and ensuring email deliverability. These policies instruct receiving mail servers on how to handle emails that fail DMARC authentication checks.
The primary goal of a DMARC policy is to enhance email security by preventing unauthorized use of your domain, but a misstep can inadvertently affect your legitimate email traffic. It’s a common concern: will quarantining emails damage my sender reputation as much as a spam complaint? Or will rejecting emails outright lead to lost legitimate mail? These are important questions we need to address.
My goal here is to clarify how p=quarantine and p=reject policies actually work, their direct and indirect effects on your sender reputation, and how they impact email delivery. We'll also explore strategies for safe implementation to ensure your emails reliably reach their intended inboxes, while bolstering your domain's security posture.
Understanding DMARC policies: quarantine vs. reject
Before diving into the effects of DMARC enforcement policies, it's helpful to quickly recap the three main policy options: p=none, p=quarantine, and p=reject. p=none is purely for monitoring, allowing you to gather data on email authentication failures without affecting delivery. This phase is crucial for ensuring all your legitimate sending sources are properly authenticated with SPF and DKIM.
When you transition to p=quarantine, you're instructing receiving mail servers to treat emails that fail DMARC authentication with suspicion. This typically means placing them into the recipient's spam or junk folder, rather than delivering them to the primary inbox. It's a way to provide a layer of protection against fraudulent emails while allowing you to continue monitoring for any legitimate emails that might still be failing authentication. The key here is that it's a *suggestion*, not a strict command, and receivers may interpret it differently.
The p=reject policy is the strongest enforcement option. With p=reject, you are instructing receiving mail servers to outright refuse emails that fail DMARC authentication. These emails are bounced and never reach the recipient's mailbox, not even their junk folder. This provides the highest level of protection against spoofing and impersonation, but it also carries the highest risk if legitimate emails are not properly authenticated, as they will be lost.
How DMARC policies influence sender reputation
A common concern when moving to an enforcing DMARC policy is its potential impact on sender reputation. Specifically, many wonder if emails sent to the junk folder under a p=quarantine policy will negatively affect their sender reputation in the same way spam complaints do. The good news is, generally, they do not.
DMARC's purpose is to authenticate the sender, verifying that the email originates from an authorized source and has not been tampered with. If an email fails DMARC (meaning SPF or DKIM alignment fails), it is considered unauthenticated, not necessarily spam. Mailbox providers treat DMARC failures differently from actual spam reports, which are direct negative feedback from users. The DMARC policy tells the receiver what to do with unauthenticated mail, helping protect your brand from spoofing, which in turn, contributes positively to your overall sender reputation. You can read more about how DMARC protects sender reputation on Mailmonitor's guide.
By actively implementing a DMARC policy, especially one of p=quarantine or p=reject, you demonstrate to mailbox providers that you are taking steps to secure your domain. This commitment to security can actually boost your sender reputation, making it more likely for your legitimate emails to reach the inbox. Mailbox providers like Google and Yahoo have recently enforced stricter DMARC requirements, underscoring its importance for all senders, particularly those sending bulk email. Understanding DMARC policies and sender reputation is key.
Real-world implications for email delivery
While a DMARC p=quarantine policy generally doesn't harm your direct sender reputation, it can still impact email delivery by sending unauthenticated emails to the junk folder. The bigger concern arises with a p=reject policy, where legitimate emails can be inadvertently blocked if they fail DMARC authentication. This often happens with email forwarding services, which can break SPF or DKIM alignment, leading to DMARC failures. In such cases, a p=reject policy would cause these legitimate emails to be lost entirely.
It's important to remember that DMARC policy is a suggestion to receiving servers. While most major mailbox providers generally honor p=quarantine and p=reject, their specific implementation can vary. For example, Microsoft's consumer mail services (like Outlook.com) might treat a p=reject policy as p=quarantine in some scenarios. This means that an email you intend to be rejected might still end up in the spam folder, rather than being completely blocked. You can learn more about how Microsoft handles DMARC policies if you encounter issues.
The critical difference for monitoring is how delivery failures are reported. With p=quarantine, legitimate emails that fail DMARC will not bounce back to you. They will simply be moved to the junk folder, and you would only become aware of this through DMARC aggregate reports. This underscores the necessity of robust DMARC reporting. Without proper monitoring, you could be unknowingly losing legitimate email traffic.
Conversely, a p=reject policy often results in bounce messages for failed legitimate emails, making these issues more immediately noticeable. While a bounce indicates a delivery failure, it also provides explicit feedback that an email was not delivered due to DMARC. This can be beneficial for quickly identifying and troubleshooting authentication problems that need to be resolved. You can dive deeper into DMARC's impact on email delivery in AWS's documentation.
Strategic implementation and monitoring
Given the potential for legitimate mail loss, I always recommend a phased approach when implementing DMARC enforcement. Starting with p=none is non-negotiable. This monitoring phase allows you to collect DMARC reports, identify all legitimate sending sources for your domain, and ensure they are properly authenticated with SPF and DKIM. It's the groundwork that prevents issues down the line.
Once you're confident that your legitimate email streams are authenticating correctly, the next step is often to move to p=quarantine. This provides a level of protection for your brand by directing suspicious emails to the spam folder, while buying you more time to identify and resolve any lingering authentication issues without causing outright delivery failures. It's a cautious but effective way to tighten security without immediately impacting legitimate email. Consider our guide on how to safely transition your DMARC policy.
Finally, with consistent DMARC authentication success for your domain, you can consider transitioning to p=reject. This step offers the highest level of protection, ensuring that any email failing DMARC is completely blocked. Continuous monitoring of your DMARC reports, even at p=reject, remains crucial to catch any unexpected issues or new sending sources that might not be properly configured.
Views from the trenches
Best practices
Always monitor your DMARC reports, especially when using a quarantine policy, to detect legitimate email failures.
Implement DMARC in phases, starting with a 'none' policy to collect data and identify all sending sources.
Resolve all SPF and DKIM authentication issues for legitimate email streams before moving to enforcing DMARC policies.
Common pitfalls
Assuming that emails quarantined due to DMARC failures negatively impact your sender reputation like spam reports do.
Transitioning directly to a reject policy without thorough testing, risking the loss of legitimate emails due to authentication issues.
Neglecting DMARC report monitoring after setting an enforcement policy, leading to unnoticed email delivery problems.
Expert tips
DMARC policies are suggestions to receiving servers, and their interpretation and enforcement can vary.
Be aware of legitimate email rejection cases, particularly with email forwarding services that can break authentication.
DMARC functions as a policy mechanism to protect your domain, rather than a general spam filter for authenticated emails.
Expert view
Expert from Email Geeks says: The primary purpose of having both quarantine and reject policies was to facilitate a gradual DMARC deployment. DMARC serves as a policy mechanism, not a spam filter, and sender reputation should be considered separately. Receiving servers may not always honor the requested policy.
2022-03-01 - Email Geeks
Expert view
Expert from Email Geeks says: If emails are placed in the junk folder due to your DMARC policy, it does not negatively impact your sender reputation in the same way a spam report would. DMARC only affects unauthenticated emails, and if legitimate mail is failing, it indicates authentication issues that need to be resolved.
2022-03-02 - Email Geeks
Achieving DMARC enforcement safely
Successfully implementing DMARC with either a p=quarantine or p=reject policy is a powerful way to bolster your domain's security and enhance your sender reputation. While p=quarantine doesn't directly harm your reputation like spam complaints, it's crucial to understand its impact on delivery by directing failed emails to junk folders. Similarly, p=reject offers the highest security but demands careful implementation to avoid blocking legitimate email.
The key takeaway is that DMARC is a policy mechanism that protects your domain and improves trust signals with mailbox providers. The perception of your domain's trustworthiness is significantly boosted when you demonstrate active security measures. This proactive stance helps build a stronger sender reputation over time, leading to better inbox placement for your legitimate mail.
A strategic, phased rollout, starting with p=none, moving cautiously to p=quarantine, and then to p=reject is the safest path. Continuous monitoring of DMARC reports is essential at every stage. When implemented correctly, the benefits of DMARC policies in preventing phishing and spoofing far outweigh the risks, securing your email ecosystem and ensuring your messages reliably reach their destination.
Google and 
Yahoo have recently enforced stricter DMARC requirements, underscoring its importance for all senders, particularly those sending bulk email. Understanding DMARC policies and sender reputation is key.
Microsoft's consumer mail services (like Outlook.com) might treat a p=reject policy as p=quarantine in some scenarios. This means that an email you intend to be rejected might still end up in the spam folder, rather than being completely blocked. You can learn more about how Microsoft handles DMARC policies if you encounter issues.
