Does DMARC improve email deliverability and should ESPs push senders to set it up?
Matthew Whittaker
Co-founder & CTO, Suped
Published 19 Jun 2025
Updated 15 Aug 2025
7 min read
DMARC, or Domain-based Message Authentication, Reporting, and Conformance, is a protocol designed to prevent email spoofing and phishing. It allows domain owners to specify how receiving mail servers should handle emails that fail SPF or DKIM authentication.
The core question I often encounter is whether DMARC directly improves email deliverability. While it's clear that DMARC helps establish a brand's trustworthiness and protects against malicious use of a domain, the relationship to inbox placement isn't always straightforward.
Many email service providers (ESPs) support DMARC, but deciding how aggressively to promote it during onboarding or with existing senders is a nuanced discussion. Is it beneficial enough to warrant pushing senders to take this extra step, or should the choice remain entirely with the domain owner?
DMARC builds upon two foundational email authentication protocols: Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM). SPF allows domain owners to publish a list of authorized sending IP addresses, while DKIM adds a digital signature to emails to verify that the message hasn't been tampered with and truly originated from the claimed domain. DMARC ties these together, instructing receivers on how to treat messages based on their SPF and DKIM authentication status and, crucially, their alignment.
For an email to pass DMARC, it must pass either SPF or DKIM, and the domain used in the From: header must align with the domain that passed SPF or DKIM. This alignment is key for DMARC to be effective. Without proper alignment, even authenticated emails might fail DMARC checks, leading to deliverability issues.
Many discussions in the email community emphasize that DMARC's primary benefit is in domain protection, rather than a direct deliverability boost. However, by preventing bad actors from spoofing your domain, you are protecting your sender reputation. A good sender reputation is, without a doubt, a cornerstone of strong email deliverability.
This example sets a policy of p=none, which is typically the starting point for DMARC implementation. It requests aggregate and forensic reports, but does not instruct receiving servers to take action on failing emails.
DMARC and its impact on deliverability
While DMARC itself doesn't directly dictate inbox placement, its enforcement policies (such as p=quarantine or p=reject) significantly impact how unauthenticated messages are handled. This can lead to a cleaner email stream for recipients, enhancing trust in legitimate senders. Many sources, including DMARC Advisor, highlight that a properly implemented DMARC policy has a positive effect on deliverability by helping to authenticate emails and reduce spam.
The indirect benefits are crucial. By deploying DMARC, you gain visibility into email streams using your domain, including legitimate and fraudulent traffic. This allows for quick identification and mitigation of spoofing attacks, which, if left unchecked, could severely damage your domain reputation and lead to emails landing in spam folders or being blocklisted. For more on this, consider reading whether DMARC improves deliverability and if p=none is useful.
It's worth noting that some mailbox providers reportedly check SPF and DKIM alignment even if a DMARC record isn't published. This implies that while DMARC provides explicit instructions and reporting, the underlying alignment of authentication records is already a factor in how mail is treated. This highlights the importance of simply having SPF and DKIM configured correctly and in alignment with your sending domain.
Impact on deliverability
Direct impact: DMARC's direct role is not to boost inbox rates, but to enforce authentication, ensuring only legitimate emails are accepted.
Policy enforcement: Policies like quarantine or reject can prevent unauthenticated mail from reaching the inbox, thus cleaning up the mail stream.
Trust and reputation
Brand integrity: Protects your domain from spoofing and phishing, preserving your brand's image and trustworthiness.
Receiver trust: Signals to mailbox providers that your domain is actively protected, potentially contributing to a better domain reputation.
The indirect benefits
Mitigating abuse: By stopping malicious emails, DMARC reduces negative signals associated with your domain.
Feedback loop: DMARC reports provide insight into authentication failures, helping to identify and fix legitimate sending issues.
Enhanced security features
Phishing prevention: Makes it harder for cybercriminals to impersonate your domain, protecting your customers.
Given DMARC's multifaceted nature, should ESPs actively push senders to implement it? The consensus leans towards strong encouragement and support, especially considering recent changes by major mailbox providers. Google’s updated sender guidelines, for instance, now explicitly require DMARC for bulk senders to ensure email delivery. This shift makes DMARC less of an optional security enhancement and more of a baseline requirement for high-volume sending.
However, it's not simply a matter of flipping a switch. DMARC implementation can be complex, particularly for organizations with multiple sending systems or third-party senders. A misconfigured DMARC record, especially with an enforcing policy like p=reject, can lead to legitimate emails being quarantined or rejected. This is why a phased approach, starting with p=none for monitoring, is crucial before moving to stricter policies.
ESPs should focus on providing robust support for DMARC alignment, rather than just DMARC itself. This means ensuring that their sending infrastructure facilitates proper SPF and DKIM alignment with the sender's domain. When an ESP aligns the domains automatically, it significantly reduces the burden on the sender and helps ensure the mail passes DMARC checks, even if the sender hasn't published their own DMARC record.
The conversation also extends to whether ESPs should force DMARC on paid customers. My view is that ESPs should educate and strongly recommend DMARC, providing tools and clear guidance for its implementation. Automatically enabling or forcing it without proper sender understanding and configuration can inadvertently break legitimate email flows, leading to significant deliverability problems and support headaches. It's a balance between promoting best practices and respecting the complexity of varied email ecosystems.
Real-world implications and advanced considerations
The true utility of DMARC often lies in its reporting capabilities, which provide invaluable insight into email authentication results and potential abuse. These reports, combined with an understanding of why your emails might be going to spam, enable senders to identify and fix issues with their legitimate email streams, thereby indirectly improving deliverability.
One area where DMARC can pose challenges is with email forwarding. When an email is forwarded, it can sometimes break the DKIM signature or SPF alignment, leading to DMARC failures for legitimate mail. This is where Authenticated Received Chain (ARC) comes into play, aiming to preserve authentication results across forwarding hops. However, ARC's adoption is still not universal, making it a current limitation for widespread DMARC enforcement.
Ultimately, DMARC should be viewed as a critical component of a comprehensive email security and deliverability strategy. It’s not a standalone fix for all deliverability woes, but rather a powerful tool that, when implemented correctly and monitored, contributes significantly to a trustworthy sending infrastructure. It helps improve trust signals, which are essential for inbox placement, and helps combat email fraud that would otherwise harm your domain's sending reputation.
Views from the trenches
Best practices
Actively monitor DMARC reports, even with a p=none policy, to understand your email ecosystem.
Prioritize proper SPF and DKIM alignment, as some mailbox providers check this even without DMARC enforcement.
Educate your team on DMARC's purpose and how it fits into your overall email strategy.
Gradually implement DMARC policies, starting with p=none, then quarantine, and finally reject, as data dictates.
Common pitfalls
Assuming DMARC is a 'set it and forget it' solution; continuous monitoring is required.
Implementing an enforcing DMARC policy (p=quarantine or p=reject) without thorough testing, risking legitimate email blocking.
Focusing solely on DMARC without ensuring the fundamental health of your email sending practices.
Failing to understand how DMARC interacts with email forwarding, potentially leading to deliverability issues for forwarded messages.
Expert tips
DMARC is not a magic bullet for deliverability, but a crucial component for domain authentication and trust.
ESPs should promote DMARC alignment and provide clear guidance, rather than forcing policies that could break legitimate mail flows.
Consider DMARC as a governance tool for email security, providing visibility and control over your domain's sending.
While DMARC itself may not directly increase deliverability, its ability to prevent spoofing significantly protects your sender reputation.
Expert view
Expert from Email Geeks says DMARC does not directly improve deliverability.
2020-08-20 - Email Geeks
Expert view
Expert from Email Geeks says DMARC deployments are complex and should not be promoted as a fire-and-forget DNS record with simple reporting.
2020-08-20 - Email Geeks
Final thoughts on DMARC and deliverability
DMARC is not a magic bullet that unilaterally boosts email deliverability. Its primary function is to provide domain protection and prevent spoofing. However, by doing so, it significantly contributes to building and maintaining a strong sender reputation, which is undeniably critical for email deliverability and ensuring your messages reach the inbox.
ESPs should certainly advocate for DMARC implementation and provide the necessary tools and guidance. The push from major mailbox providers means DMARC is no longer just a best practice, but a de facto requirement for reliable bulk sending. The focus for ESPs should be on facilitating proper SPF and DKIM alignment, alongside comprehensive DMARC reporting, to empower senders to make informed decisions and secure their email channels effectively. By doing this, we help ensure a safer and more reliable email ecosystem for everyone.
