Does a DMARC record need to be associated with the _dmarc subdomain?
Michael Ko
Co-founder & CEO, Suped
Published 17 May 2025
Updated 19 Aug 2025
7 min read
When setting up DMARC for your domain, a common question arises: does the DMARC record truly need to be associated with the specific _dmarc subdomain? It's a detail that might seem minor, but it's foundational to how DMARC functions and, by extension, to your email deliverability and security.
Many guides on how to implement DMARC often show the _dmarc subdomain in examples, leading to the assumption that it is a mandatory part of the setup. This article clarifies why this specific subdomain is not just a convention, but a strict requirement as defined by the DMARC standard.
Understanding this requirement is crucial for ensuring your emails are properly authenticated, protecting your domain from spoofing, and maintaining high inbox placement rates. Let's delve into the specifics of why this subdomain is indispensable for DMARC.
The fundamental requirement of the _dmarc subdomain
The DMARC standard, formally defined in RFC 7489, explicitly states that DMARC policy records must be published as DNS TXT records within a subdomain named _dmarc. For instance, if your domain is example.com, the DMARC record would be located at _dmarc.example.com. This naming convention is not optional; it's a fundamental aspect of how email receivers discover and apply your domain's DMARC policy.
This standardized location ensures that mail servers worldwide can reliably find and interpret your DMARC instructions. Without this specific subdomain, a receiving mail server would not know where to look for your DMARC policy, effectively rendering your DMARC implementation invisible and ineffective. It's similar to how an A record points to a web server for a website, or an MX record directs mail to an email server. DMARC simply has its own designated spot.
RFC 7489 defines it
Section 6.1 of RFC 7489 explicitly details the requirement: "Domain Owner DMARC preferences are stored as DNS TXT records in subdomains named "_dmarc".
This is the authoritative source that mandates the _dmarc subdomain for DMARC records.
This structural requirement ensures that DMARC operates predictably across the internet. When a mail receiver receives an email, it extracts the domain from the From header (RFC5322.From) and then constructs the specific query _dmarc.yourdomain.com to retrieve the DMARC policy. This process is standardized, meaning there's no room for variation in where the record is placed.
Even for subdomains, while a DMARC policy can be inherited from the organizational domain, an explicit DMARC record for a subdomain must still be placed in its respective _dmarc subdomain (e.g., _dmarc.sub.example.com) if you intend for that subdomain to have a policy that differs from the organizational domain's policy. This is further explained in our guide on how DMARC records on subdomains override root policies.
How DMARC records are located
Mail receivers perform a DNS lookup for the DMARC record by prepending _dmarc to the domain found in the email's From header. This is the primary mechanism for DMARC policy discovery. If a DMARC record is not found at this precise location, the receiver will assume no DMARC policy is in place for that domain or subdomain.
This lookup process also governs policy inheritance. If an email is sent from a subdomain (e.g., marketing.example.com) and there is no specific DMARC record at _dmarc.marketing.example.com, the receiving server will then look for a DMARC record at the organizational domain, _dmarc.example.com. This is why a single organizational DMARC record can cover all subdomains by default, unless overridden. For more details, refer to our article, Do subdomains need their own DMARC records?
Correct DMARC record placement
Location: Always published as a TXT record at _dmarc.yourdomain.com. This is the universal identifier for DMARC policies.
Policy inheritance: Subdomains inherit the parent domain's DMARC policy by default, unless they have their own explicit _dmarc record, as discussed in how the DMARC sp tag affects subdomain policies.
Mail receivers: They perform an immediate DNS query to this precise subdomain to fetch the DMARC record and apply the specified policy for authentication and reporting.
The consistency of this lookup process is vital for the global adoption and effectiveness of DMARC as an email authentication standard. It allows receiving mail servers to quickly and accurately determine how to handle incoming mail based on the sending domain's explicit policies.
Implications for email authentication and deliverability
Failing to associate your DMARC record with the _dmarc subdomain can have significant negative implications for your email deliverability and security posture. Without the record in its designated spot, your DMARC policy will simply not be discovered by receiving mail servers.
This means that even if you have proper SPF and DKIM records configured, DMARC's critical role in instructing mail receivers on how to handle unauthenticated mail (e.g., quarantine or reject) will be bypassed. Emails failing authentication might still reach the inbox, but they are also more likely to be marked as spam or rejected outright, especially by major providers like Yahoo and Google. These providers require DMARC for bulk senders as part of their new 2024 email sender requirements.
Crucially, without DMARC enabled, your domain is more susceptible to email spoofing and phishing attacks. Bad actors can send emails appearing to come from your domain, potentially damaging your brand reputation and leading to blocklisting (or blacklisting). This is why a correctly configured DMARC record is a cornerstone of modern email security. Learn more about the benefits of implementing DMARC.
Setting up your DMARC record
Setting up your DMARC record correctly is a straightforward but critical step in enhancing your email security and deliverability. The record itself is a TXT record, and it must include various tags that define your DMARC policy, such as v (version), p (policy), and rua (aggregate report URI). You can find a comprehensive list of DMARC tags and their meanings in our guide.
Here's an example of a DMARC record that you would publish as a TXT record under the _dmarc subdomain of your domain:
This record instructs receiving mail servers to apply a policy of p=none (monitor mode) and send aggregate reports to the specified email address. This is a common starting point for DMARC implementation, allowing you to gather data before enforcing stricter policies. For assistance, consider using our free DMARC record generator to create your record, and follow our guide on how to properly set up DMARC records.
Key takeaways for domain owners
In summary, the _dmarc subdomain is a non-negotiable component of DMARC implementation. Its strict definition in the DMARC standard (RFC 7489) ensures that mail receivers can universally locate and apply your domain's DMARC policy, which is essential for effective email authentication and preventing abuse.
Ensuring your DMARC record is correctly published at _dmarc.yourdomain.com is a foundational step for protecting your email ecosystem, improving deliverability, and complying with modern email sender requirements. Regular DMARC monitoring can help you verify correct setup and identify any issues.
Views from the trenches
Best practices
Always publish your DMARC record as a TXT record under the `_dmarc` subdomain for your domain.
Start with a `p=none` policy to gather aggregate DMARC reports without impacting email delivery.
Monitor your DMARC reports regularly to understand email authentication results and identify potential issues.
If using subdomains for email, consider if separate DMARC records are needed to override organizational policies.
Ensure your SPF and DKIM records are correctly configured and aligned, as DMARC relies on them.
Common pitfalls
Publishing the DMARC record directly on the root domain instead of the `_dmarc` subdomain.
Not having any DMARC record, leaving the domain vulnerable to spoofing and phishing.
Moving directly to `p=reject` or `p=quarantine` without first analyzing DMARC reports.
Forgetting to update DMARC records when changing email service providers or sending infrastructure.
Misinterpreting DMARC reports, leading to incorrect adjustments or missed issues.
Expert tips
Utilize DMARC aggregate reports (`rua`) to gain insights into legitimate and illegitimate email traffic.
Implement a DMARC policy even for domains that don't send email to prevent abuse (e.g., `p=reject`).
Be mindful of the `sp` tag if setting policies specifically for subdomains versus the organizational domain.
Leverage DMARC tools to simplify record generation, management, and report analysis.
Continuously review and refine your DMARC policy as your email sending practices evolve.
Expert view
Expert from Email Geeks says the DMARC record absolutely needs to be published at `_dmarc.domainName`.
2024-01-24 - Email Geeks
Expert view
Expert from Email Geeks says that this requirement is part of RFC 7489, which standardizes how DMARC works.
Google. These providers require DMARC for bulk senders as part of their new 2024 email sender requirements.
