Why does Google Postmaster require a TXT record for a subdomain when the main domain is already verified?

Key findings

• Independent data: Google Postmaster Tools requires separate TXT record verification for a subdomain if you wish to view its data independently of the main domain. If you want the subdomain's data to roll up, a separate verification is often not strictly required.
• Domain vs. subdomain: Each domain or subdomain is often treated as a distinct entity by Google's systems for comprehensive data collection and reputation tracking.
• Verification purpose: The TXT record verifies ownership of the specific domain or subdomain to prevent unauthorized use and ensure accurate data reporting.
• User permissions: Sometimes, the need for re-verification can stem from user account permissions, where the person adding the subdomain is not the same person or account that initially verified the root domain.

Key considerations

• Strategic subdomain use: Consider if you truly need separate data for each subdomain, which would necessitate individual verification. For instance, transactional emails often use a different subdomain from marketing emails to protect their sending reputation.
• Ownership consistency: Ensure the Google account attempting to add the subdomain has the necessary permissions or is associated with the original domain verifier.
• DNS records: Be prepared to add specific TXT records for each subdomain you wish to track independently. Ensure your DNS records are correctly configured, as incorrect records can lead to verification failures. You can learn more about Google's domain verification process.

Key opinions

• Conflicting instructions: Some marketers find Google's documentation unclear on when a subdomain requires separate verification versus when it can be automatically included under a verified main domain.
• Unexpected verification: The request for a TXT record for a subdomain can be surprising, especially if another subdomain under the same main domain was added without such a prompt.
• Ownership confusion: It is sometimes hypothesized that the Google account used to add the subdomain might not have been the same one that verified the root domain, leading to the re-verification prompt.
• Granular data desired: Many marketers understand that individual subdomain verification is necessary if they want to see distinct reputation metrics for that specific sending entity.

Key considerations

• Verify separately for independence: If you need detailed reputation data for a specific subdomain, verifying it independently with a TXT record is the most reliable approach.
• Check previous verification: Before adding a subdomain, confirm which Google account verified the main domain to streamline the process and avoid unnecessary re-verification prompts.
• Understand Google's nuances: Be aware that Google's systems can sometimes behave unpredictably or require specific verifications depending on internal logic and desired data granularity. For more details on common issues, see how to use Google Postmaster Tools effectively.

Key opinions

• Separate entities: Experts confirm that Google Postmaster Tools often treats each domain and subdomain as a distinct entity requiring its own verification record.
• Granular control: The purpose of separate verification for subdomains is to allow for granular data and reputation tracking, rather than just a consolidated view.
• CNAME preference: Some experts recommend using CNAME verification over TXT records for Google Postmaster Tools to avoid DNS clutter, especially with multiple records.
• Verification flexibility: While Google allows subdomains to be added under a root verification for aggregated data, specific verification is needed if separate Postmaster data is desired for that subdomain.

Key considerations

• Adopt CNAMEs for simplicity: To streamline DNS management and potentially prevent issues with crowded TXT records, consider using CNAME verification where possible.
• Plan for subdomain reputation: If you are using subdomains for different email types, proactively set them up for individual tracking in Postmaster Tools to monitor their specific performance and prevent deliverability issues on one subdomain from impacting another.
• Adhere to best practices: Regardless of main domain verification, ensure each sending subdomain has proper SPF, DKIM, and DMARC records configured, as these are fundamental for email authentication and deliverability.

Key findings

• Security measure: Google requires domain verification to prevent unauthorized parties from using a domain or its subdomains for various Google services.
• Primary verification method: The DNS TXT record is the most common method Google provides for domain ownership verification in Postmaster Tools.
• Independent data vs. aggregation: Documentation states that while a verified main domain allows adding subdomains for aggregated data, independent verification is needed to view separate data for individual subdomains.
• Ownership proof: Adding the provided TXT record to your DNS proves ownership of the specific domain or subdomain to Google.

Key considerations

• Follow specific instructions: Always refer to the exact instructions provided by Google Postmaster Tools for each domain or subdomain you wish to verify, as the process can be specific to your use case.
• Consider CNAME option: Be aware that Google sometimes offers CNAME verification as an alternative to TXT records, which may be preferable in certain DNS configurations.
• Understand data segmentation: If your goal is to analyze the reputation of distinct email streams, separate subdomain verification is not merely a technical step but a prerequisite for accurate reporting.