Summary
For senders using a top-level domain for their From address but signing emails with a DKIM authenticated subdomain, the question of whether to monitor both domains for deliverability metrics is crucial. While Google Postmaster Tools (GPT) V2 aggregates some data at the top-level domain, ignoring subdomain-specific data can lead to missed insights into reputation variances, complaint rates, and overall deliverability issues. Monitoring both offers a more granular view and helps in proactively addressing potential problems.
Key findings
- Reputation variance: Subdomains can independently develop their own sender reputation, which may differ significantly from the parent (top-level) domain.
- Data granularity: Monitoring subdomains provides more specific data points on performance, complaints, and blocklisting, which is essential for targeted troubleshooting.
- DKIM alignment: While the reputation is largely tied to the DKIM signed domain, friendly From domains also play a role in how recipients and ISPs perceive your mail.
- Complaint source: Email complaints are typically attributed to the DKIM signed domain, making its monitoring critical for identifying abusive sending patterns.
Key considerations
- Comprehensive view: To gain a full understanding of your email program's health, monitor both the top-level domain and all active DKIM subdomains.
- DMARC reports: Utilize DMARC monitoring to receive aggregated reports on authentication results, which will include data for both your organizational domain and its subdomains.
- Strategic subdomain use: Implement a strategy where different subdomains are used for distinct mail streams (e.g., transactional, marketing) to isolate reputation and simplify troubleshooting. This is a common best practice, as outlined in our guide on why to use subdomains.
- Authentication importance: Ensure proper SPF and DKIM authentication for all sending domains and subdomains to maintain strong deliverability. Mailjet provides a comprehensive guide on authenticating domains with SPF and DKIM.
What email marketers say
Email marketers widely acknowledge the importance of monitoring subdomains, even when the friendly From domain is the top-level domain. They emphasize that while some reporting tools might consolidate data, the underlying reputation and complaint signals are often tied to the DKIM signing domain or specific sending subdomains. This makes granular monitoring essential for effective deliverability management and quick issue resolution.
Key opinions
- Subdomain reputation: Many marketers find that subdomains can develop distinct reputations from their parent domains, warranting separate monitoring.
- Monitoring is key: Despite some platforms rolling data into the top-level domain, marketers still see value in verifying and monitoring DKIM authenticated subdomains.
- Data for troubleshooting: The detailed data from subdomains, especially concerning complaints, helps in diagnosing and resolving deliverability issues more effectively.
- Reputation complexity: Email reputation is not solely tied to one domain type, but influenced by various factors across all sending entities.
Key considerations
- Distinct mail streams: Using different subdomains for different email types (e.g., transactional, marketing) is widely recommended to protect overall domain reputation. Our guide on using subdomains for outbound email elaborates on this.
- DKIM's role: Reputation and complaints are often linked to the DKIM signed domain. This means understanding the best DMARC, DKIM, and SPF setup is vital.
- From domain considerations: While DKIM is primary for reputation, the friendly From domain still impacts user perception and some filter decisions. Mailgun's article on the basics of email subdomains offers insights.
Marketer view
Marketer from Email Geeks suggests that you definitely want to monitor subdomains because they can have a different reputation from the parent domain. They experienced a client where the parent domain showed a medium reputation, but transactional and marketing subdomains had high and low reputations respectively, highlighting the variance.
Marketer view
Marketer from Email Geeks confirms that while they usually monitor both the top-level and DKIM subdomains, they need a sanity check because reputation is often tied to the DKIM signed domain (d= tag). They believe that even if the friendly From domain is the root, there should still be variances in reputation and complaints for the DKIM domain.
What the experts say
Email deliverability experts consistently advise granular monitoring for all sending domains and subdomains. They highlight that while DMARC enforcement focuses on the aligned domain (often the DKIM domain), all components of an email, including the friendly From domain and Return-Path, contribute to the overall sender reputation. Therefore, neglecting to monitor any part of the sending infrastructure can create blind spots, leading to undetected deliverability issues that impact inbox placement.
Key opinions
- Holistic reputation: Experts stress that email reputation is a complex calculation influenced by all aspects of the email, not just the DKIM signing domain.
- Monitoring depth: It is critical to monitor all domains and subdomains involved in sending, including the friendly From, Return-Path, and DKIM domains.
- Isolation strategy: Using separate subdomains for different email types (e.g., marketing, transactional) helps isolate reputation risks, preventing issues in one stream from affecting others.
- Visibility gaps: Failing to monitor any significant domain or subdomain can lead to undetected problems and potential blocklistings.
Key considerations
- Comprehensive analysis: Implement robust monitoring tools that provide insights across all your sending domains and subdomains. This aligns with advice on technical solutions for deliverability.
- DNS configurations: Proper DNS setup, including SPF and DKIM records for all relevant domains, is foundational for good deliverability. Kickbox Blog offers expert advice on how DNS impacts email deliverability.
- Proactive issue detection: Continuous monitoring of all domain types allows for early detection of issues, preventing them from escalating into major deliverability problems. Discover common email deliverability issues.
Expert view
Deliverability Expert from Email Geeks notes that reputation is multifaceted and tied to every element of your email sending. Therefore, a comprehensive monitoring strategy should encompass all active domains and subdomains involved in your email streams, even if certain tools aggregate data differently.
Expert view
Deliverability Expert from Email Geeks advises that while the DKIM signed domain heavily influences reputation, neglecting the friendly From domain or other sending subdomains can lead to overlooked issues. All domains that a recipient sees or that authenticate the message should be monitored.
What the documentation says
Technical documentation and official guidelines strongly advocate for comprehensive monitoring and proper configuration of all domains and subdomains involved in email sending. This is primarily because email authentication protocols like DMARC, SPF, and DKIM operate at the domain level, and their proper alignment is critical for message acceptance. Documentation emphasizes that even if an email appears to originate from a top-level domain, its underlying authentication often relies on specific subdomains, making their individual monitoring indispensable for compliance and deliverability.
Key findings
- Authentication standards: For an email to pass DMARC, it must pass either SPF or DKIM alignment, where the domain used in those checks aligns with the RFC 5322 From domain.
- Subdomain coverage: Many guidelines recommend ensuring all subdomains are covered under SPF, DKIM, and DMARC policies for full protection.
- DKIM's role in DMARC: A valid DKIM signature and alignment between the d= tag (DKIM domain) and the From domain are essential for DKIM-based DMARC compliance.
- Reputation isolation: Official advice often encourages using subdomains to compartmentalize different mail streams, thereby limiting the scope of potential damage from reputation issues.
Key considerations
- Holistic authentication: Implement SPF, DKIM, and DMARC across all top-level domains and their respective subdomains. Our simple guide to DMARC, SPF, and DKIM covers the basics.
- DMARC policy for subdomains: Consider if subdomains need their own DMARC records or if a wildcard DMARC record (e.g., *.yourdomain.com) is appropriate to protect all subdomains.
- Proactive protection: The Canadian Centre for Cyber Security provides implementation guidance on email domain protection, emphasizing the importance of comprehensive authentication.
Technical article
Documentation from Mailjet Help Center explains that for DMARC compliance based on DKIM, the message must have a valid DKIM signature, and the From domain must align with the DKIM signing domain. This underscores the need to monitor the DKIM subdomain as it is crucial for authentication.
Technical article
Documentation from Platform Documentation (Webex Connect) states that for an email to comply with DMARC, it must pass either SPF or DKIM alignment. The domain used in these checks must align with the domain in the RFC 5322 From header, making all relevant domains critical to monitor.
Related resources
15 resources
Related pages
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