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

Email marketer from Super User community shares that in a multi-tenant environment, a separate TXT record might be needed on a subdomain for verification to ensure that each tenant (or subdomain) is properly authenticated and authorized to use Google services. This prevents unauthorized access and maintains the integrity of the email ecosystem.

Email marketer from Quora suggests that Google might prompt for a subdomain TXT record because the initial domain verification was performed some time ago, and Google's security policies have since been updated. Re-verifying with a new TXT record for the subdomain brings the account in line with current standards.

Email marketer from Webmaster World forum user mentions that in some cases, Google Postmaster Tools might require separate subdomain verification to provide more granular reporting and insights for each subdomain. This allows for tracking the reputation and performance of different sending domains independently, which is beneficial for identifying and resolving issues specific to one subdomain.

Email marketer from DigitalOcean Community emphasizes that subdomain-specific TXT records are essential for implementing distinct SPF, DKIM, and DMARC configurations for each subdomain. This targeted approach to email authentication ensures that each subdomain's email sending practices are properly validated and protected, boosting deliverability and reputation.

Email marketer from Reddit explains that sometimes Google Postmaster requests separate TXT records for subdomains because each subdomain might be treated as a distinct sending source. This is especially relevant if the subdomain is used for different types of email (e.g., marketing vs. transactional), requiring separate SPF, DKIM, and DMARC settings.

Email marketer from Stack Overflow shares that Google requires separate TXT records for subdomains even if the main domain is verified, particularly for services like Google Apps (now Google Workspace), to confirm that the subdomain is also under your control and properly configured for its specific use. This is a security and administration best practice.

Expert from Email Geeks explains that if the main domain is verified, any subdomain can be added without additional verification records. However, if each subdomain was registered separately, each one requires its own record.

Expert from Email Geeks suggests that the Google Postmaster might require the original domain verifier to add subdomains, implying permissions are tied to the user who initially verified the main domain.

Expert from Word to the Wise forum explains that Google may require a separate TXT record for subdomains to enable more granular reputation tracking and management. This allows senders to monitor and address deliverability issues specific to individual subdomains, which is crucial for maintaining overall email program health.

Documentation from Google Workspace Admin Help explains that while Google generally allows inheriting verification for subdomains once the main domain is verified, specific Google services or configurations might still require individual subdomain verification via TXT records to ensure granular control and security policies are applied correctly. This is especially true when subdomains are treated as separate entities with distinct settings.

Documentation from Google Domains Help clarifies that while domain verification generally covers subdomains, there can be exceptions for Google Workspace. These exceptions require separate TXT records on the subdomain to enable specific features or enforce unique policies at the subdomain level, ensuring better segmentation and security.

Documentation from MXToolbox details that DNS configurations, including TXT records, are hierarchical but not always inherited. For Google services, a specific TXT record on a subdomain ensures that any policies or settings associated with that subdomain are explicitly authorized and controlled, which is more secure than implicit inheritance.