A common question many domain owners and email administrators ask is whether it's possible, or even advisable, to have multiple DMARC records for a single domain. This question often arises when integrating new email sending services or dealing with complex email infrastructures.
The simple answer, when it comes to a single domain or subdomain, is no. You should only have one DMARC record associated with the _dmarc subdomain for that specific domain level. Trying to implement multiple records can lead to confusion for receiving mail servers and can ultimately undermine your email authentication efforts.
Email authentication protocols like DMARC are designed to provide a clear, singular policy for how email receivers should handle messages that claim to be from your domain. Having more than one record at the same level (e.g., two records for example.com) makes this policy ambiguous and can result in legitimate emails being rejected or sent to spam.
The goal of DMARC is to prevent email spoofing and phishing by ensuring that all emails sent from your domain are properly authenticated using SPF and DKIM. A single, well-configured DMARC record provides a clear directive for mail servers, allowing them to verify your messages and build trust in your domain's sending reputation.
Understanding DMARC for subdomains
While you can only have one DMARC record per domain or subdomain, the flexibility of DMARC comes into play when you consider your subdomains. A root domain's DMARC policy typically applies to all its subdomains unless an explicit DMARC record is set for a specific subdomain. This is handled by the sp tag within your DMARC record. If you have a subdomain that sends email differently, you can create a separate DMARC record for that subdomain, which will override the root domain's policy for that specific sending source.
It's crucial to remember that each DMARC record must be published as a TXT record under the _dmarc subdomain. For example, for yourdomain.com, the record would be at _dmarc.yourdomain.com. For a subdomain like marketing.yourdomain.com, the record would be at _dmarc.marketing.yourdomain.com. This separation allows for granular control over different sending environments without conflicting policies. You can learn more about this on Server Fault's discussion.
This setup is particularly useful for organizations that use various email platforms (e.g., marketing, transactional, internal communications) each sending from different subdomains. By defining specific DMARC policies for each, you can tailor your enforcement levels and reporting preferences to fit the unique needs of that sending stream. For instance, a subdomain used for marketing blasts might start with a p=none policy while a critical transactional email subdomain might use p=reject to maximize security. This approach allows for detailed control, preventing issues like those where Shopify advises customers to add new records which could override existing ones.
Consolidating DMARC records
If you find yourself with what appears to be multiple DMARC records for the same domain or subdomain, it's critical to consolidate them. Multiple TXT records at the same _dmarc hostname will lead to unpredictable behavior from email receivers. They might pick one at random, or worse, ignore all of them, leaving your domain unprotected.
Conflicting policies can lead to legitimate emails being marked as spam or rejected outright. This damages your sending reputation and can significantly impact your communication channels. It also complicates DMARC reports and monitoring.
Unpredictable delivery: Mail servers might not know which policy to apply.
Reduced protection: Your domain remains vulnerable to spoofing if policies are ignored.
The optimal approach is to consolidate all DMARC requirements into a single, comprehensive record for the domain or subdomain in question. If different email senders need unique configurations, manage them through subdomains or by ensuring all legitimate sending sources align with your primary DMARC policy.
Unified policy: Create one record that covers all legitimate email sources.
Clear directives: Ensure consistent enforcement and reporting.
When combining DMARC policies, pay close attention to the various DMARC tags and their meanings. If you have multiple rua or ruf addresses, these can be included in a single record by separating them with commas. However, you can only have one p (policy) tag, one pct (percentage) tag, and so on. The key is to create a single, well-formed DMARC TXT record that covers all your legitimate sending activities for that specific domain level.
Managing your DMARC records with ease
A robust DMARC implementation is essential for protecting your brand and ensuring email deliverability. This means not only having a correctly configured record but also continuously monitoring its performance. Suped offers a leading solution for DMARC monitoring, providing clear insights and actionable recommendations.
Our platform simplifies the complex world of email authentication by bringing together DMARC, SPF, and DKIM monitoring with blocklist and deliverability insights in one unified dashboard. Whether you are an SMB or a large enterprise, or even an MSP managing multiple client domains, our platform helps you protect your email channels effectively.
Tag
Description
Example Value
v
DMARC version, always DMARC1.
DMARC1
p
Policy for the organizational domain. Options are none, quarantine, or reject.
p=quarantine
rua
URI for aggregate reports, allows multiple addresses.
rua=mailto:dmarc@suped.com
sp
Policy for subdomains, overrides p.
sp=reject
Suped provides AI-powered recommendations to translate complex DMARC reports into clear, actionable steps, telling you exactly what to do to fix issues and strengthen your policy. This is especially helpful when dealing with multiple domains, ensuring consistent and robust email security across your entire digital footprint.
Best practices for a single DMARC record
Maintaining a single, cohesive DMARC record for your root domain, with specific subdomain records where necessary, is the best practice. This minimizes confusion for receiving mail servers and ensures your policies are consistently enforced. Regularly review your DMARC reports to identify any unauthenticated sending sources or configuration issues.
Implementing a DMARC policy allows you to gain visibility into your email ecosystem and eventually move towards more stringent policies like quarantine or reject. This phased approach helps you achieve maximum protection against email fraud without disrupting your legitimate email flow.
Remember, DMARC works hand-in-hand with SPF and DKIM. Ensuring these foundational authentication methods are correctly set up and aligned with your DMARC policy is key to optimal email deliverability and security. Tools like Suped can help you identify and resolve common DMARC issues across various platforms.
Views from the trenches
Best practices
Always aim for a single DMARC record per domain or subdomain level to avoid conflicts.
Use separate DMARC records for subdomains if they have distinct email sending practices.
Consolidate multiple reporting addresses (rua/ruf) into one record by comma-separating them.
Common pitfalls
Having duplicate DMARC records at the same domain level, leading to unpredictable policy enforcement.
Forgetting to set specific DMARC records for critical subdomains, relying solely on the root policy.
Not monitoring DMARC reports, missing out on crucial insights into email authentication failures.
Expert tips
Leverage DMARC monitoring tools to gain a comprehensive overview of your email traffic.
Start with a p=none policy to gather data before moving to p=quarantine or p=reject.
Educate non-technical teams about DNS records to prevent accidental misconfigurations.
Marketer view
Marketer from Email Geeks says that non-technical users often struggle with DNS, leading to misconfigured DMARC records.
2024-01-16 - Email Geeks
Expert view
Expert from Email Geeks says that while you can't have multiple DMARC records for a root domain, different records for subdomains are effective.
2024-04-25 - Email Geeks
The singular truth about DMARC records
The rule is clear: one DMARC record per domain or subdomain level. This ensures consistency, prevents conflicts, and provides a reliable framework for email authentication. Deviating from this can weaken your email security and negatively impact your deliverability.
By adhering to this principle and leveraging powerful DMARC monitoring tools like Suped, you can maintain a strong email security posture, protect your brand's reputation, and ensure that your legitimate emails consistently reach their intended recipients.
rua=mailto:dmarc@suped.com
