Summary
Primary domain authentication has complex effects on subdomain deliverability and compliance. While organizational domain compliance is assessed broadly, subdomains also have independent reputations. Subdomains require their own authentication records (SPF, DKIM, DMARC), as these are not inherited. A primary domain's DMARC policy impacts subdomains based on the 'sp' tag setting. Each subdomain requires its own delegated DNS records. Subdomains sending different email types may benefit from separate IPs. It's crucial to monitor subdomain deliverability separately. Sender reputation is linked to both domain and IP, impacting overall deliverability. Addressing spam complaints remains crucial, and spam spikes can arise from test emails mistakenly delivered to inboxes. Poor authentication or sending practices on subdomains can affect overall sender reputation, especially if IPs are shared. Properly implemented DMARC records with subdomain policies are vital to prevent unauthorized use.
Key findings
- Compliance and Subdomains: Organizational domain compliance affects subdomains, but subdomains maintain independent reputations.
- Authentication Independence: Subdomains need their own SPF, DKIM, and DMARC records, not inherited from the primary domain.
- DMARC Impact on Subdomains: Primary domain DMARC policies influence subdomains via the 'sp' tag setting, influencing deliverability depending on the policies of the organisational domain and subdomains.
- DNS Delegation Essential: Proper DNS delegation is crucial for each subdomain, ensuring accurate routing and authentication.
- IP Segregation Benefits: Separate IPs for subdomains sending distinct email types can isolate reputation.
- Monitor Subdomain Deliverability: Separate monitoring of subdomain deliverability is essential for identifying and addressing problems.
- Reputation Links: Sender reputation is linked to the domain and IP, meaning subdomain practices impact overall reputation.
- Spam and Complaints: Addressing complaints and being cautious with testing procedures is vital for healthy deliverability.
Key considerations
- Configure Subdomain Authentication: Ensure proper SPF, DKIM, and DMARC records are set up for each subdomain.
- DMARC Subdomain Policy: Carefully configure the DMARC 'sp' tag for subdomain policy management.
- Consider Separate IPs: Consider using separate IPs for different email types sent by subdomains.
- Implement Monitoring: Monitor subdomain deliverability separately to identify and resolve issues.
- Manage Reputation Proactively: Actively manage sender reputation for both the primary domain and subdomains.
- Review DNS Settings: Verify delegated DNS records for each subdomain.
- Minimize Spam Complaints: Take steps to reduce spam complaints and be careful when testing.
What email marketers say
8 marketer opinions
Primary domain authentication significantly influences subdomain deliverability and compliance, but subdomains also maintain independent reputations. While compliance is generally calculated at the organizational domain level, subdomains each require their own authentication records (SPF, DKIM, DMARC) for optimal deliverability. DMARC policies on the primary domain can affect subdomains based on configuration. Subdomains sending different types of email may benefit from separate IPs. Monitoring subdomain deliverability is essential, as poor authentication or sending practices can negatively impact sender reputation, particularly if sharing IPs with the primary domain.
Key opinions
- Compliance Scope: Compliance is typically assessed at the organizational domain level, but impacts extend to subdomains.
- Independent Reputation: Subdomains possess individual reputations, separate from the primary domain. Poor practices on one don't automatically affect the others, except when the primary domain has bad practices that impact subdomains.
- Authentication Records: Each subdomain requires its own authentication records (SPF, DKIM, DMARC) for proper validation.
- DMARC Impact: The DMARC policy of the primary domain influences subdomain handling, especially concerning the subdomain policy (`sp`) tag.
- Sender Reputation: Sender reputation ties to both the domain and IP address, thus poor subdomain authentication impacts overall reputation.
- Separate IPs: Subdomains using distinct IPs for varying email types (marketing vs. transactional) can isolate and protect reputation.
Key considerations
- Authentication Configuration: Ensure proper SPF, DKIM, and DMARC records are configured for each subdomain.
- Subdomain Policy: Carefully configure the DMARC subdomain policy (`sp` tag) to manage how unauthenticated subdomains are handled.
- IP Segregation: Consider using separate IPs for subdomains sending different types of email to isolate reputation.
- Deliverability Monitoring: Implement independent deliverability monitoring for each subdomain to identify and address issues promptly.
- Reputation Management: Actively manage the sender reputation of both the primary domain and its subdomains.
Marketer view
Email marketer from Mailjet shares that subdomains have their own reputation, separate from the primary domain. Poor sending practices on a subdomain can negatively impact its deliverability without directly affecting the primary domain's reputation, although the reverse is true when bad behaviour is on the primary domain.
21 Apr 2022 - Mailjet
Marketer view
Email marketer from Reddit explains that a DMARC policy on the primary domain can affect subdomains, depending on the policy's configuration (specifically, the `sp` tag for subdomain policy). A strict DMARC policy on the primary domain can cause deliverability issues for subdomains that don't have their own DMARC records.
27 Jan 2025 - Reddit
What the experts say
6 expert opinions
While compliance with list-unsubscribe may not always directly correlate with deliverability, addressing spam complaints is crucial. Spam spikes can be triggered by tests that unintentionally send mail to the inbox, resulting in negative reactions. Subdomains should have their own authentication records, as primary domain failures can affect them depending on DMARC policy. Configuring SPF records for all subdomains sending email is important, and a strong DMARC policy on the organizational domain applies to subdomains unless otherwise specified, influencing deliverability.
Key opinions
- Complaint Impact: Reducing spam complaints is critical for improving deliverability.
- Spam Spike Trigger: Spam spikes can result from tests that inadvertently send mail to the inbox, leading to immediate negative feedback.
- SPF Importance: SPF records are essential for each subdomain to ensure email authentication and prevent deliverability issues.
- DMARC Policy Influence: The DMARC policy on the primary domain can affect how subdomains are handled unless a specific subdomain policy is defined.
- Subdomain Authentication: Subdomains require their own authentication records to mitigate deliverability issues, especially if the primary domain experiences authentication failures.
Key considerations
- Complaint Monitoring: Monitor and address spam complaints to maintain a positive sender reputation.
- Testing Practices: Review testing procedures to prevent unintentional delivery of mail to the inbox, which can trigger spam spikes.
- SPF Configuration: Properly configure SPF records for all subdomains sending email.
- DMARC Implementation: Implement and carefully configure a DMARC policy, including subdomain policy, to manage email authentication and deliverability.
- Authentication Review: Regularly review and update authentication records for both the primary domain and subdomains.
Expert view
Expert from Spam Resource explains that subdomains should have their own authentication records to avoid deliverability issues. If the primary domain fails authentication, subdomains may be impacted depending on the DMARC policy and sender reputation.
22 Jul 2022 - Spam Resource
Expert view
Expert from Email Geeks suggests that a spam spike could be due to a test where the mail went out of spam into the inbox for that day, and people saw mail they hadn't seen because it was going to spam and they immediately reacted negatively to it.
23 Dec 2023 - Email Geeks
What the documentation says
5 technical articles
Proper subdomain delegation, requiring specific DNS records, is vital for correct routing and authentication. SPF records are independently assessed for each subdomain and do not inherit from parent domains. DKIM signatures should be configured for both primary and subdomains to ensure email authentication. DMARC policies can be applied specifically to subdomains using the `sp` tag to manage authentication failures. A correctly implemented DMARC record, inclusive of subdomain policies, helps prevent unauthorized subdomain use, necessitating consistent monitoring and enforcement of DMARC across all sending domains and subdomains.
Key findings
- Subdomain Delegation: Proper delegation of subdomains via DNS records is critical for routing and authentication.
- SPF Independence: SPF records are evaluated independently for each subdomain; inheritance from parent domains does not occur automatically.
- DKIM Requirements: DKIM signatures need to be configured for both primary domains and all sending subdomains to ensure proper authentication.
- DMARC Policies: DMARC provides specific policies applicable to subdomains, controlled via the subdomain policy (`sp`) tag.
- Unauthorized Use Prevention: A fully implemented DMARC record, including subdomain policies, is crucial in preventing the unauthorized use of subdomains.
Key considerations
- DNS Configuration: Ensure proper DNS records are created when delegating subdomains for email sending.
- SPF Record Management: Create and maintain distinct SPF records for each subdomain sending email.
- DKIM Setup: Implement DKIM signatures for both the primary domain and all subdomains used for sending emails.
- DMARC Policy Definition: Define appropriate DMARC policies, including subdomain policies, to manage authentication failures on subdomains.
- DMARC Monitoring and Enforcement: Continuously monitor and enforce DMARC records on all sending domains and subdomains to prevent unauthorized use.
Technical article
Documentation from DMARC.org explains that DMARC has specific policies that can be applied to subdomains. The subdomain policy (`sp`) tag in a DMARC record allows domain owners to specify how DMARC should handle authentication failures on subdomains.
17 Feb 2024 - DMARC.org
Technical article
Documentation from Google Workspace Admin Help explains that delegating a subdomain involves creating DNS records that point to Google's servers. Properly delegating subdomains is crucial for ensuring emails are correctly routed and authenticated.
5 Apr 2024 - Google Workspace Admin Help
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How can I resolve DMARC verification failures when using a subdomain for email sending?
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How do subdomain deliverability issues affect parent domains, and what are the primary causes of email deliverability problems?
