Summary
The question of whether a DMARC record must be associated with the _dmarc subdomain is fundamental to proper email authentication and deliverability. While it might seem like a common practice, understanding the underlying requirements from official specifications and practical implications is crucial.
Key findings
- RFC requirement: According to RFC 7489, DMARC policy records are explicitly stored as DNS TXT records in subdomains named _dmarc.
- Standard practice: Mail receivers query this specific subdomain to discover a domain's DMARC policy, making it a universal standard for DMARC implementation.
- Subdomain policies: While the _dmarc subdomain is standard for the organizational domain, individual subdomains can (and often should) have their own DMARC records to define specific policies or override the parent domain's policy. Read more about DMARC record placement for subdomains.
- Inheritance: Without an explicit DMARC record on a subdomain, it will inherit the policy of its organizational parent domain, which may not always be desirable.
- Visibility: Placing the DMARC record at _dmarc.yourdomain.com ensures that all compliant email receivers can easily locate and apply your specified policy.
Key considerations
- Consistency: Always publish your DMARC record at the _dmarc subdomain for the domain you wish to protect.
- Subdomain management: Even if your main domain has a DMARC record, consider if subdomains need their own DMARC records based on their sending behavior.
- Policy enforcement: Proper placement ensures your p= policy (none, quarantine, reject) is correctly enforced by recipient mail servers.
- Avoiding confusion: While many guides explain DMARC setup, some might omit the explicit mention of the _dmarc subdomain, leading to potential confusion for new implementers.
What email marketers say
Email marketers often encounter DMARC implementation as a technical hurdle, particularly regarding DNS record placement. While many follow standard guides, the specific requirement for the _dmarc subdomain can be a point of inquiry, especially when dealing with multiple subdomains or complex sending architectures.
Key opinions
- Common confusion: Many marketers acknowledge that while the _dmarc subdomain is common, explicit documentation making it a must can be elusive.
- Subdomain strategy: Marketers frequently question the need for separate DMARC records for subdomains, with some advocating for explicit records on all sending subdomains to ensure granular control and protection.
- Following guides: Most follow general setup guides that implicitly use the _dmarc subdomain without necessarily understanding the RFC mandate.
- Deliverability impact: The focus is often on ensuring emails deliver reliably, with the technical specifics of DMARC record placement sometimes being secondary to achieving inbox placement. Learn more about email deliverability issues.
Key considerations
- Mandatory placement: Even if not explicitly stated in every 'how-to' guide, the _dmarc subdomain is the only location where a DMARC record will be discovered and processed by receiving mail servers.
- Simplified setup tools: Many email service providers (ESPs) and DNS managers automatically handle the _dmarc subdomain, abstracting this detail from the user.
- Reporting: Correct DMARC record setup, including placement, is essential for receiving DMARC reports which are vital for monitoring email authentication and identifying potential abuse. Consider troubleshooting DMARC reports.
- SPF and DKIM alignment: While DMARC itself lives at _dmarc, its effectiveness relies on proper SPF and DKIM authentication, which are configured separately.
- Understanding documentation: Even if the RFC is dense, understanding its key points can help marketers implement DMARC correctly and avoid common pitfalls. A guide on how to add a DMARC record can be a helpful resource.
Marketer view
Marketer from Email Geeks wondered if the _dmarc subdomain association was a strict requirement, noting that general documentation often implies it as the norm but doesn't explicitly state it as a must-have.
Marketer view
Marketer from Email Geeks expressed surprise that major email provider documentation does not always explicitly state the necessity of the _dmarc subdomain in their 'How to add DMARC records' guides.
What the experts say
Experts in email deliverability and authentication unequivocally state that the DMARC record must be associated with the _dmarc subdomain. This is not merely a convention but a requirement stipulated by the RFC that defines DMARC.
Key opinions
- RFC compliance is key: The mandate for DMARC records to reside at _dmarc is directly from RFC 7489, which is the foundational document for DMARC.
- Universal discovery: Mail receivers are programmed to query _dmarc.yourdomain.com to find DMARC policies; any other location will not be recognized.
- Documentation clarity: While end-user guides might not always highlight this explicitly, the underlying technical standards are very clear on the required subdomain.
- Subdomain policy inheritance: Experts emphasize that while a parent domain's DMARC policy can apply to subdomains, explicit subdomain DMARC records (also at _dmarc.subdomain.yourdomain.com) are often necessary for fine-tuned control or to override organizational policies. For more, see how DMARC policy works with subdomains.
Key considerations
- Strict adherence: Deviation from the _dmarc subdomain naming convention will lead to DMARC records not being discovered or applied.
- No sp for explicit subdomain records: When setting an explicit DMARC record for a subdomain, the sp tag within the parent domain's DMARC record becomes irrelevant for that specific subdomain. Understand how the DMARC sp tag works.
- Importance of RFCs: Relying on RFCs for email standards (like DMARC) is paramount, as they provide the definitive rules for how email systems interact.
- Comprehensive DMARC setup: A robust DMARC implementation involves not just the _dmarc subdomain for the main domain but also careful consideration of DMARC setup best practices for all subdomains that send email.
Expert view
Expert from Email Geeks clarified that the DMARC record must be published at _dmarc.domainName, confirming it as a mandatory standard.
Expert view
Expert from Email Geeks emphasized that the requirement for DMARC record placement is an RFC 7489 standard, not merely a preference from major email providers like Yahoo or Google.
What the documentation says
The authoritative documentation, primarily RFC 7489, explicitly defines the required placement for DMARC records. This ensures consistent discovery and application of DMARC policies across the global email ecosystem.
Key findings
- Mandatory subdomain: RFC 7489, section 6.1, unequivocally states that DMARC policy records are stored as DNS TXT records in subdomains named _dmarc.
- Discovery mechanism: Mail receivers perform a TXT query to the DNS for _dmarc.example.com to find the DMARC preferences for example.com.
- Record type: A DMARC record is always a TXT record, not other DNS record types like NS records, as confirmed by technical documentation. Find out more about DMARC tags.
- Subdomain inheritance and explicit policies: Documentation clarifies that subdomains without explicit DMARC policies inherit the organizational domain's policy, but individual subdomains can have their own policies to override this. DMARC supports separate subdomain policies.
Key considerations
- Compliance: To be DMARC compliant and ensure your policy is honored, the record must be placed at the _dmarc subdomain.
- Setup consistency: Official guides from various providers (e.g., IONOS) consistently demonstrate creating the DMARC record with the _dmarc subdomain name.
- Comprehensive protection: Implementing DMARC at _dmarc provides a robust defense against email spoofing and phishing, requiring careful configuration of the DMARC policy to achieve desired enforcement levels. Consider simple DMARC examples.
- Role of DNS: The DNS system acts as the backbone for DMARC, ensuring that policies are publicly discoverable at the specified _dmarc location.
Technical article
Documentation from RFC 7489, Section 6.1, specifies that DMARC policy records are consistently stored as DNS TXT records within subdomains named "_dmarc" for any given domain.
Technical article
Documentation from IONOS Help states that DMARC policies are implemented as TXT records, specifically using the subdomain name "_dmarc" (e.g., _dmarc.example.com).
Related resources
13 resources
Related pages
What is the best practice for DMARC record placement for subdomains?
Do subdomains need their own DMARC records if the main domain has one?
A simple guide to DMARC, SPF, and DKIM
The benefits of implementing DMARC
How do I set up DMARC records for subdomains?
What are the best practices for DMARC setup, including organizational and subdomain policies and reporting?
List of DMARC tags and their meanings
How to safely transition your DMARC policy to quarantine or reject
How does DMARC policy application work with subdomains and CNAME records?
Understanding and troubleshooting DMARC reports from Google and Yahoo
