Can I set DMARC to reject if my domain doesn't send email?
Michael Ko
Co-founder & CEO, Suped
Published 12 Aug 2025
Updated 12 Oct 2025
8 min read
The question of whether to set a DMARC policy to p=reject for domains that don't send email is quite common. It's a smart security move, and the short answer is yes, absolutely. If a domain isn't meant to send any emails, implementing a DMARC policy of p=reject is a robust way to prevent unauthorized parties from spoofing your domain and using it for malicious activities like phishing. This effectively tells receiving mail servers to immediately block any email claiming to be from your domain if it doesn't pass DMARC authentication. I often advise this as a foundational step for protecting your brand's digital presence.
The purpose of DMARC p=reject for non-sending domains
When a domain doesn't send email, it becomes a prime target for spoofing. Cybercriminals often look for domains without proper email authentication, such as SPF, DKIM, and DMARC, because they can easily impersonate these domains to launch phishing attacks or send spam. By setting DMARC to p=reject, you're explicitly instructing email receivers to reject all emails that fail DMARC checks, effectively shutting down any attempts to use your domain maliciously. This is a critical step in combating email spoofing and protecting your brand's reputation.
This measure goes beyond simply preventing deliverability issues. It's about proactive security. A domain with no DMARC record, or one set to p=none, is essentially an open invitation for attackers. Even if you aren't sending emails, the mere existence of your domain can be exploited if not properly secured. The DMARC reject policy acts as a clear signal to the entire email ecosystem that any unauthenticated mail from your domain is fraudulent and should be blocked.
Boost your domain's security
Setting a DMARC p=reject policy for domains not used for email sending significantly enhances security. It ensures that mail providers like Gmail and Yahoo will reject emails that falsely claim to originate from your domain. This minimizes the risk of your brand being associated with spam or phishing campaigns, protecting your reputation and your potential customers.
It's a straightforward and powerful way to secure your entire domain portfolio, including those dormant or parked domains.
It’s important to understand how DMARC, SPF, and DKIM records should be configured for these non-sending domains. Even though they don't send email, having SPF and DKIM records, even if minimal, alongside DMARC can reinforce the message that no legitimate mail should originate from them. This comprehensive approach ensures maximum protection.
Before you set DMARC to reject
Before you set DMARC to p=reject, you need to be absolutely certain that no email, under any circumstances, should originate from that domain or any of its subdomains. This includes automated system messages, contact form submissions, or internal alerts. An overlooked email source could lead to legitimate messages being rejected, causing potential disruptions. Take the time to conduct a thorough audit of all potential email-sending systems associated with that domain. I have seen situations where a web server or an old application was still configured to send emails using the main domain, leading to unexpected rejections after a p=reject policy was implemented.
Website forms: Check all contact forms, registration forms, or any other forms on your website that might send email notifications.
System alerts: Review any monitoring tools, servers, or applications that send automated alerts or reports using the domain.
Third-party services: Ensure no third-party services (e.g., CRM, marketing automation) are configured to send emails from this specific domain.
Subdomains: Remember that a DMARC record can apply to subdomains. Verify if any subdomains are sending email that might be impacted.
In addition to DMARC, it's a good practice to set up SPF and DKIM records for non-sending domains. For SPF, you can use a record that explicitly states no mail is authorized to send from this domain. For example, "v=spf1 -all". DKIM can be set up with a dummy record or by simply not publishing any valid DKIM keys, ensuring that any email attempting to use DKIM for your domain will fail. This multi-layered approach strengthens your domain's defense against unauthorized use.
Many organizations begin their DMARC journey with a p=none policy to gather data, but for non-sending domains, this exploratory phase is often unnecessary. Since no legitimate email is expected, you can often jump straight to p=reject without the risk of blocking genuine mail, provided you've done your due diligence in verifying no sending occurs. This strategy is also recommended by authoritative sources like Cloudflare's guide on protecting domains that do not send email.
Implementing the DMARC record
The implementation of a DMARC p=reject record for a non-sending domain is relatively straightforward. You'll need to add a TXT record to your domain's DNS. The key components are v=DMARC1 and p=reject. It's also highly advisable to include a rua tag to receive aggregate reports. Even for non-sending domains, these reports can alert you to unexpected email attempts from your domain, which is a sign of spoofing or a misconfigured internal system. Microsoft Learn provides guidance on setting up DMARC, which is applicable here.
DMARC p=none for non-sending domains
While common for sending domains during the initial DMARC rollout, p=none (monitoring policy) on a non-sending domain means that emails that fail DMARC checks will still be delivered. This provides data via DMARC reports but doesn't actively prevent spoofing. It might satisfy a basic checker but leaves your domain vulnerable.
Vulnerability: Allows spoofed emails to reach inboxes.
Reputation risk: Your brand could still be associated with spam.
No active protection: Doesn't prevent unauthorized usage.
DMARC p=reject for non-sending domains
This is the recommended policy for domains that should never send email. It instructs receiving mail servers to outright reject any email that fails DMARC authentication for your domain. This provides the highest level of protection against spoofing and phishing, ensuring that no unauthorized emails from your domain ever reach an inbox.
Strong protection: Actively prevents spoofed emails from being delivered.
Brand integrity: Safeguards your brand's reputation from abuse.
Clear signal: Explicitly tells receivers to block unauthorized mail.
Remember that DMARC processing can apply to your organizational domain and its subdomains. If you have subdomains that also don't send email, the DMARC record for the main domain (if set with sp=reject or implicitly through relaxed alignment) will protect them as well. However, it's a good idea to consider explicit DMARC records for critical subdomains to ensure consistent enforcement.
Monitoring and maintaining your DMARC policy
Even with a p=reject policy in place for a non-sending domain, continuous monitoring is a vital best practice. The aggregate DMARC reports, sent to the email address specified in your rua tag, will provide valuable insights. These reports will show you if any mail servers are still attempting to send email using your domain, even if they are ultimately rejected. This information can reveal hidden configurations or persistent spoofing attempts that you might need to address.
At Suped, we offer a robust DMARC monitoring platform that helps you easily parse and analyze these reports. Even for non-sending domains, our tool can consolidate these reports into an understandable format, allowing you to quickly spot any anomalies. This ensures that your p=reject policy is working as intended and that your domain remains secure from unauthorized use. It’s an essential part of maintaining your email security posture.
Regularly reviewing DMARC reports, even for domains that don't send mail, helps in understanding and troubleshooting DMARC issues and can provide early warnings about potential security threats. While the goal is to see zero legitimate emails failing authentication, any unexpected entries in the reports warrant investigation. This proactive approach is key to comprehensive domain protection and preventing your brand from being blacklisted (or blocklisted) by receiving mail servers due to impersonation.
Views from the trenches
Best practices
Always perform a thorough audit of all systems and subdomains before implementing p=reject.
Include SPF and DKIM records for non-sending domains to reinforce authentication.
Use a DMARC monitoring tool to review reports for any unexpected sending attempts.
Communicate the intentional policy to senior management to avoid misunderstandings.
Consider a simple 'v=spf1 -all' SPF record for maximum protection.
Common pitfalls
Overlooking hidden email-sending sources like contact forms or internal system alerts.
Failing to account for subdomains that might inadvertently send email.
Assuming no DMARC record is needed since the domain doesn't send mail.
Not monitoring DMARC reports for non-sending domains, missing spoofing attempts.
Setting p=reject without confirming zero legitimate email sending.
Expert tips
A DMARC p=reject policy is a strong security signal for non-sending domains.
Even minimal or dummy SPF/DKIM records are beneficial alongside DMARC.
Reports can highlight forgotten email sources or active spoofing attempts.
For non-sending domains, you can typically skip the p=none monitoring phase.
Document the decision to use p=reject for compliance and internal clarity.
Expert view
Expert from Email Geeks says that as long as no mail is sent with that domain, or any subdomain or superdomain of it in the From: address, then setting p=reject is perfectly acceptable and recommended.
September 22, 2020 - Email Geeks
Marketer view
Marketer from Email Geeks suggests looking for any contact forms, CRM integration, or web server sending technical reports to administrators before implementing a p=reject policy.
September 22, 2020 - Email Geeks
Final thoughts on DMARC reject for non-sending domains
For domains that are not intended to send email, setting a DMARC policy of p=reject is not just permissible, but highly advisable for robust security. It provides an unequivocal instruction to mail servers worldwide to reject any email that attempts to impersonate your domain, thus protecting your brand from being used in phishing or spam campaigns. This simple yet powerful configuration closes a significant security loophole that many organizations overlook.
However, the key to success lies in a thorough pre-implementation audit to ensure no legitimate email sources are inadvertently missed. Once confirmed, a p=reject policy, complemented by appropriate SPF and DKIM records, offers maximum protection. Remember to also utilize DMARC reporting tools, such as the one available at Suped, to continuously monitor for any unauthorized activity. This layered approach ensures your non-sending domains are secure and your brand's reputation is safeguarded.
Gmail and 
Yahoo will reject emails that falsely claim to originate from your domain. This minimizes the risk of your brand being associated with spam or phishing campaigns, protecting your reputation and your potential customers.
DMARC monitoring platform that helps you easily parse and analyze these reports. Even for non-sending domains, our tool can consolidate these reports into an understandable format, allowing you to quickly spot any anomalies. This ensures that your p=reject policy is working as intended and that your domain remains secure from unauthorized use. It’s an essential part of maintaining your email security posture.
