Summary
There's no definitive consensus on whether Google Postmaster Tools (GPT) includes subdomains in the root domain's reputation calculation. Some data suggests Google explicitly tells users subdomains are not included, yet inconsistencies are seen in GPT data. Experts and marketers recommend using subdomains to isolate reputation and separate different email types (transactional vs. marketing). However, the root domain remains essential for reputation checks. Google's documentation requires authentication for data visibility but is vague on aggregation. RFC standards define subdomains as separate, and it is very important to warm them up before starting a campaign.
Key findings
- GPT Inconsistency: Conflicting signals from Google and observed GPT data make it unclear if subdomains are factored into the root domain reputation.
- Reputation Isolation: Using subdomains is a common strategy to isolate reputation and protect the main domain.
- Root Domain Importance: The root domain remains the foundational element for reputation assessment.
- Authentication Required: Data in Postmaster Tools is only available for authenticated domains (SPF, DKIM, DMARC).
- RFC Standard: Subdomains are defined as separate domains according to RFC standards.
Key considerations
- Subdomain Strategy: Implement a clear strategy for using subdomains to manage and isolate email sending reputation.
- Monitor GPT Data: Carefully monitor GPT data for both the root domain and subdomains, being aware of potential inconsistencies.
- Authentication: Ensure proper authentication (SPF, DKIM, DMARC) is in place for all sending domains and subdomains.
- Subdomain Warmup: Warm up subdomains properly before launching any campaigns to develop a healthy sending reputation.
- Type Separation: Consider the types of email you are sending and split into different subdomains.
What email marketers say
10 marketer opinions
Experts and marketers offer conflicting views on whether Google Postmaster Tools (GPT) domain reputation includes subdomains. Some sources report explicit statements from Google indicating subdomains are not included in the organizational domain's reputation. However, others express doubt, noting that GPT sometimes displays a reputation even when the organizational domain itself doesn't send mail. Further, differing GPT reputations are observed for parent domains and subdomains. The use of subdomains is generally recommended for isolating reputation and separating different types of email traffic (e.g., transactional vs. marketing), but root domains are still the core part of where reputation is checked.
Key opinions
- Google's Stance: Some users have been told by Google that organizational domain reputation excludes subdomains.
- GPT Discrepancies: GPT sometimes shows a reputation even when the organizational domain isn't sending emails, creating uncertainty.
- Reputation Isolation: Using subdomains can help isolate reputation issues, preventing them from affecting the primary domain.
- Root Domain Importance: Root domains are critical, as they are the core component of reputation checks.
- Separate Reputations: Parent domains and subdomains have shown completely different GPT representations.
Key considerations
- Subdomain Usage: Consider using subdomains for different types of email (marketing, transactional) to manage reputation effectively.
- Warm-up Subdomains: If implementing subdomains for sending, ensure they are properly warmed up to establish a good sending reputation.
- Monitoring: Continuously monitor GPT for both parent domains and subdomains to identify and address any deliverability issues.
- Trusting GPT Data: The accuracy of GPT data should be approached with caution, given observed discrepancies.
- Protect Reputation: Separate your domain and subdomain to protect your domain reputation.
Marketer view
Email marketer from Stackoverflow user says root domains are always needed and are the core part of where the reputation is checked.
21 Feb 2023 - Stackoverflow
Marketer view
Email marketer from Sendgrid explains the benefits of dedicated sending domains and subdomains for better control over your sending reputation and improved deliverability.
14 Jan 2023 - Sendgrid
What the experts say
5 expert opinions
Experts offer insights into how Google Postmaster Tools (GPT) handles domain and subdomain reputation. One expert assumes root domain reputation includes subdomains. While focusing on the d= for reputation, there's a suggestion Google might include subdomains in root calculations, separating it out with the FBL identifier. Other experts emphasize using subdomains to protect the primary domain's reputation by isolating different types of email traffic and their reputation.
Key opinions
- Reputation Mixing: Root domain reputation may be a mix of mail with that d= and any d= subdomain.
- FBL Identifier: Google might include subdomains in the root calculation but separate it with the FBL identifier.
- Reputation Focus: Focus on the d= (DKIM domain) for reputation analysis.
- Reputation Isolation: Subdomains can isolate reputation, protecting the primary domain.
Key considerations
- Subdomain Strategy: Use subdomains for different email types (transactional, marketing) to protect your primary domain's reputation.
- FBL Analysis: Pay attention to the FBL identifier in Postmaster Tools to understand how Google handles subdomain data.
- DKIM Alignment: Ensure DKIM alignment is correctly configured for both your primary domain and subdomains.
- Reputation Monitoring: Monitor both domain and subdomain reputation in Postmaster Tools to proactively address issues.
Expert view
Expert from Email Geeks shares her assumption that the root domain reputation is a mix of mail with that d= and mail with any d= that is a subdomain.
28 Jan 2022 - Email Geeks
Expert view
Expert from Spamresource suggests using subdomains to protect your primary domain’s reputation, especially for different types of email (transactional vs. marketing).
14 Nov 2023 - Spamresource
What the documentation says
6 technical articles
Google's documentation states that Postmaster Tools data is aggregated for domains passing authentication (SPF, DKIM, DMARC), and authentication is required to view the data. However, it doesn't clarify if subdomains are aggregated into the root domain's reputation or kept separate. Other documentation sources (RFC, Microsoft, Cloudflare) confirm that subdomains are distinct domains, treated differently from the top-level domain, and that domain names form the base of email and web addresses.
Key findings
- Data Aggregation: Postmaster Tools data is aggregated for authenticated domains.
- Authentication Required: SPF or DKIM authentication is needed to see data in Postmaster Tools.
- Subdomain Clarity Lacking: Google's documentation doesn't explicitly state if subdomain reputation is separate or aggregated.
- Separate Domains: RFC defines subdomains as separate domains.
- Domain Addresses: Domain names are the basis for email and web addresses.
Key considerations
- Domain Authentication: Ensure proper SPF, DKIM, and DMARC setup for both the main domain and subdomains to ensure data is tracked.
- Experiment and Monitor: Since Google's documentation is unclear, closely monitor both domain and subdomain reputations to understand Google's behavior.
- Subdomain Isolation: The separation of subdomains provides potential for reputation isolation, so configure sending accordingly.
- Leverage Tools: Utilize Postmaster Tools to get insights into how google is tracking/rating different parts of your sending infrastructure.
Technical article
Documentation from Microsoft says that your domain name is the address that appears after the @ sign in email addresses, and after www. in web addresses.
12 Jan 2023 - Microsoft
Technical article
Documentation from Google Help details that Postmaster Tools provides an overview of your domain's reputation with Google, but doesn't explicitly state whether subdomains are aggregated into the root domain reputation calculation or kept separate.
8 Jul 2024 - Google Help
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