Why is my primary domain not compliant with Google one-click unsubscribe while the subdomain is?
Michael Ko
Co-founder & CEO, Suped
Published 18 Apr 2025
Updated 18 Aug 2025
7 min read
It can be perplexing to see your primary domain flagged as non-compliant for Google's one-click unsubscribe requirements, especially when a subdomain appears to be in good standing. This scenario often arises due to the nuances of how email providers, particularly Google, assess domain compliance and reputation. While your subdomain might be meticulously configured for marketing sends, issues on the primary domain can silently impact its overall standing.
The key lies in understanding that email service providers (ESPs) and mailbox providers often attribute the reputation and compliance status of subdomains back to the primary (or root) domain. Even if you're not actively sending emails from your.primary.com, issues like unauthenticated mail streams or legacy configurations can affect it. This can lead to a situation where a clean subdomain's efforts are overshadowed by problems on the parent domain.
One-click unsubscribe, mandated by Google and Yahoo for bulk senders, relies on specific email headers that allow recipients to easily opt-out. When your primary domain is flagged, it suggests that these headers are either missing, improperly formatted, or that the associated unsubscribe process is failing for emails tied to that root domain, directly or indirectly.
Understanding Google Postmaster Tools
Google Postmaster Tools (GPT) acts as a crucial barometer for your email sending health. While it provides detailed insights, its compliance status dashboard, particularly for one-click unsubscribe, primarily reflects the health of the primary domain. This means that data from both the primary domain and its subdomains are used to determine compliance for the primary domain itself.
It's a common misconception that if a subdomain is compliant, the primary domain is automatically fine. Google's documentation confirms that while subdomain data contributes, the ultimate compliance status is often tied to the root. Therefore, a non-compliant primary domain can impact the deliverability of even well-configured subdomains. You should monitor your Google Postmaster Tools carefully.
How Google Postmaster Tools sees domains
The Postmaster Tools dashboard for compliance status specifically focuses on the primary domain. Even if your email traffic primarily flows through subdomains, the aggregated data regarding unsubscribe compliance will funnel up and reflect on the root domain’s status. This consolidation means a hidden issue on the root can appear as a broad non-compliance problem.
If your.primary.com isn't used for sending, a non-compliant status likely indicates unauthenticated mail, or forged emails using your primary domain. This can occur if malicious actors are spoofing your domain, or if there's shadow IT sending from it without proper authentication (SPF, DKIM, DMARC).
The importance of DMARC visibility
One of the most critical elements in diagnosing this issue is analyzing your DMARC reports. DMARC, or Domain-based Message Authentication, Reporting, & Conformance, gives you visibility into all email sending from your domain, including unauthorized sources. A DMARC record, even with a p=none policy, will provide XML reports (aggregate reports) detailing who is sending email using your domain, whether it's authenticated (SPF and DKIM aligned), and its disposition (delivered, quarantined, or rejected).
The reason a primary domain might show non-compliance while a subdomain is compliant, even without direct sending from the primary, points to unauthenticated email. This could be anything from internal systems you're unaware of (often called "shadow IT"), to phishing attempts where bad actors are spoofing your primary domain. These unauthenticated emails, even if low volume, can significantly damage your primary domain's reputation and lead to non-compliance flags for features like one-click unsubscribe, which Gmail prioritizes.
To gain clarity, ensure you have a DMARC record published for your primary domain. This will allow you to receive aggregate reports and identify any unauthorized sending sources that might be impacting your primary domain's reputation or causing it to appear non-compliant with Google Postmaster Tools.
One-click unsubscribe implementation
Google and Yahoo's one-click unsubscribe requirement is tied to the presence and proper functioning of specific email headers, primarily the List-Unsubscribe and List-Unsubscribe-Post headers, as outlined in RFC 8058. If your primary domain is showing non-compliance, it could mean that emails implicitly or explicitly associated with it are missing these headers, or that the associated unsubscribe links are not working correctly according to the RFC.
Even if your subdomain sends are perfectly configured with these headers, if there are any other mail streams originating from or associated with your primary domain that lack this functionality, it could trigger the non-compliant flag in GPT. This applies to transactional emails, forgotten internal systems, or even corporate 1:1 emails that might not typically be considered bulk but can still affect your domain's overall perception.
Primary domain issues
Unauthenticated sending: Mail sent directly from the primary domain without proper SPF or DKIM alignment.
Shadow IT: Internal systems (dev, support, sales) sending email without proper DMARC and unsubscribe headers.
Forged emails: Malicious actors spoofing your primary domain, leading to compliance flags.
Subdomain compliance
Dedicated ESPs: Properly configured email service providers (ESPs) handle SPF, DKIM, and one-click unsubscribe for subdomains.
Controlled traffic: Subdomains typically have fewer, more controlled sending sources, making compliance easier to maintain.
Isolation: Good subdomain practices isolate their reputation from primary domain issues to a degree, but not entirely.
The existence of List-Unsubscribe headers is non-negotiable for bulk senders. If your primary domain's status is problematic, it's crucial to investigate all possible email streams under that domain, even dormant ones, to ensure they're not inadvertently causing the issue. This might involve auditing your DNS records for forgotten senders or checking for unauthorized DMARC failures.
Reputation and root domain influence
Sender reputation is holistic. While subdomains can help segment your email traffic and manage reputation for specific sending purposes, the reputation of the primary domain remains foundational. A poor reputation on the primary domain, perhaps due to spam complaints, inclusion on a blacklist, or even a blocklist, can negatively influence the deliverability and compliance status of its subdomains.
If Google Postmaster Tools is flagging your primary domain for one-click unsubscribe compliance, it's a strong indicator that Google's systems perceive a broader issue with your domain's email practices, not just isolated to your marketing subdomains. This could stem from high spam complaint rates associated with the root domain, even if these complaints are about emails sent from previously unknown sources.
To mitigate this, you must thoroughly audit all sending sources for your primary domain. This includes identifying any rogue senders or misconfigured internal systems that might be impacting your overall sender reputation. Implementing DMARC with monitoring is the most effective way to gain this comprehensive visibility.
Understanding why your primary domain is marked as non-compliant while your subdomain is compliant often comes down to a few key areas. It's about auditing all email-sending activities tied to your primary domain, not just the ones you actively manage for marketing. Resolving these hidden issues is crucial for maintaining a strong sender reputation and ensuring long-term email deliverability.
Views from the trenches
Best practices
Always implement DMARC with a p=none policy to gain full visibility into all email sources using your domain, including primary and subdomains.
Regularly review your DMARC aggregate reports to identify unauthorized sending or misconfigurations.
Ensure all email streams, including transactional and corporate 1:1, comply with one-click unsubscribe requirements.
Verify that
Common pitfalls
Assuming subdomain compliance means the primary domain is automatically compliant.
Ignoring DMARC reports, leading to unaddressed shadow IT or spoofing issues.
Overlooking internal systems or legacy applications that send unauthenticated emails from the primary domain.
Not implementing the
Expert tips
Leverage Google Postmaster Tools, particularly the IP and Domain Reputation dashboards, for clues.
If your primary domain isn't used for sending, check for DMARC failures pointing to forged mail.
Work with your IT and development teams to identify and secure any hidden sending systems.
Consider segmenting email types (marketing, transactional) to specific subdomains for better control.
Expert view
Expert from Email Geeks says that forged mail or corporate 1:1 mail could be the reason for primary domain non-compliance.
2024-02-05 - Email Geeks
Marketer view
Marketer from Email Geeks says that setting up DMARC provides necessary visibility into all mail sources.
2024-02-05 - Email Geeks
Key takeaways
The distinction between your primary domain and its subdomains, while useful for managing specific email campaigns, dissolves when it comes to overall domain reputation and compliance in the eyes of major mailbox providers like Google. The primary domain acts as the umbrella, and any issues under it can affect the perception of your entire email ecosystem.
To resolve a primary domain's non-compliance for one-click unsubscribe, you must undertake a thorough audit of all email sending activities associated with it. This includes leveraging DMARC reports to uncover hidden or unauthenticated mail streams, ensuring all sending systems properly implement the necessary unsubscribe headers, and proactively addressing any activities that could diminish your primary domain's reputation. Ultimately, comprehensive vigilance across all sending points linked to your primary domain is key to achieving and maintaining full compliance.
Google, assess domain compliance and reputation. While your subdomain might be meticulously configured for marketing sends, issues on the primary domain can silently impact its overall standing.
Yahoo for bulk senders, relies on specific email headers that allow recipients to easily opt-out. When your primary domain is flagged, it suggests that these headers are either missing, improperly formatted, or that the associated unsubscribe process is failing for emails tied to that root domain, directly or indirectly.
