The question of whether a parent (organizational) domain needs a BIMI (Brand Indicators for Message Identification) record for a subdomain's BIMI to display is common among senders managing complex domain structures. While a parent domain BIMI can offer inheritance, it is not a strict prerequisite for a subdomain to successfully implement and display its own BIMI logo. The critical factor for any domain or subdomain using BIMI is the proper configuration and enforcement of DMARC (Domain-based Message Authentication, Reporting, and Conformance) at the organizational level.
Key findings
Subdomain BIMI: A BIMI record can be published directly on a subdomain and will be honored by mailbox providers, even if the parent domain lacks its own BIMI record.
Inheritance: A BIMI record published at the organizational domain (parent domain) can be inherited by subdomains, provided the subdomain does not have its own explicit BIMI record.
DMARC requirement: For BIMI to function on any domain or subdomain, a valid DMARC policy (at p=quarantine or p=reject) must be published at the organizational domain level.
DNS propagation: DNS changes, including new BIMI records, require time to propagate globally before they are consistently recognized by BIMI lookup tools and mailbox providers.
Key considerations
DMARC alignment: Ensure your DMARC record is properly configured for the organizational domain. This is non-negotiable for BIMI to work, whether on the parent or a subdomain. Learn how to set up DMARC for BIMI.
DNS configuration: Verify the exact hostname and value for your BIMI TXT record on your DNS server. Errors here are a common cause of BIMI not appearing.
Selector usage: While BIMI selectors allow for publishing multiple logos (similar to DKIM selectors), most mailbox providers currently only honor the default selector. This is detailed in the BIMI Group's FAQ for Senders.
Validation tools: Use online BIMI lookup tools to confirm your record is correctly published and detected.
What email marketers say
Email marketers often encounter challenges and questions when implementing BIMI, particularly concerning subdomain setups and interactions with parent domains. The common sentiment is that while BIMI offers significant branding advantages, its dependency on a robust DMARC implementation can be a hurdle, especially when managing multiple domains or subdomains. Marketers frequently seek clarity on whether they need to control the parent domain's DNS for subdomain BIMI to work and how to troubleshoot visibility issues.
Key opinions
Parent domain control: Many marketers inquire if the parent domain's lack of BIMI prevents a subdomain's BIMI from functioning, often finding it does not, as long as DMARC is correctly enforced.
DNS troubleshooting: A frequent issue is the BIMI record not being found by lookup tools, pointing towards DNS configuration problems rather than inheritance issues.
DMARC as foundation: Marketers emphasize the absolute necessity of a correctly configured DMARC policy on the organizational domain before BIMI can be activated on any subdomain.
Visual benefits: Despite the technical complexities, the visual branding benefits of BIMI, such as logo display, are highly valued by marketers for enhancing email authenticity and trust.
Key considerations
Timelines for display: It's important to set realistic expectations for logo display, as DNS propagation and mailbox provider caching can cause delays after BIMI is set up.
Brand consistency: Consider how BIMI implementation for subdomains aligns with overall brand strategy, especially if different logos are used across subdomains.
Verification: Regularly check your BIMI record's validity to ensure continuous logo display and authentication.
Marketer view
Marketer from Email Geeks asks whether the parent domain requires a BIMI record for a subdomain's BIMI to display, noting they struggled for a year to get their subdomain BIMI string working.
22 Jul 2022 - Email Geeks
Marketer view
Marketer from Email Geeks observes that their subdomain BIMI is not being found by the BIMI Group's online generator tool, indicating a replication issue.
22 Jul 2022 - Email Geeks
What the experts say
Email deliverability experts highlight that BIMI's flexibility allows for implementation at both the organizational domain and subdomain levels, without requiring a parent BIMI for subdomain functionality. However, they consistently emphasize that the underlying DMARC authentication must be robustly in place at the organizational domain for BIMI to be recognized. Experts also clarify the nuances of BIMI inheritance and the current state of support for various BIMI selectors across mailbox providers.
Key opinions
Subdomain independence: Experts confirm that a subdomain can have its own BIMI record, even if the organizational domain does not.
DMARC primacy: The fundamental requirement for BIMI on any domain is a properly configured and enforced DMARC policy at the organizational domain level.
Inheritance rules: A parent domain's BIMI can be inherited by subdomains, but a sub-subdomain cannot inherit from a subdomain. This is similar to how DMARC policies apply to subdomains.
Selector adoption: While BIMI selectors are defined, most mailbox providers do not yet honor non-default selectors, meaning broad adoption is still pending.
Key considerations
DNS accuracy: Precise DNS record creation is crucial. Any slight error in the BIMI TXT record's hostname or value will prevent it from being found.
BIMI record search: The search for a BIMI record first checks the specific domain in the RFC5322.From header, then falls back to the organizational domain.
Future use of selectors: Although currently limited, non-default selectors might be used in the future for scenarios like seasonal logos or specific branding initiatives.
Consulting official sources: For complex setups or specific questions, experts recommend reaching out directly to the BIMI Group.
Expert view
Expert from Email Geeks states that if BIMI is set up on the organizational domain, it will be inherited by any qualifying subdomain, and Verified Mark Certificates (VMCs) can also be configured in a similar way.
22 Jul 2022 - Email Geeks
Expert view
Expert from Email Geeks confirms that BIMI can indeed be deployed exclusively on a subdomain if that is the chosen setup preference.
22 Jul 2022 - Email Geeks
What the documentation says
Official BIMI documentation and related standards clearly outline the technical requirements for BIMI implementation, including its interplay with domain hierarchy and DMARC. The specifications confirm that while a BIMI record can be found at the organizational domain and apply to subdomains, explicit subdomain BIMI records take precedence. Crucially, the documentation reinforces DMARC as the foundational authentication protocol necessary for BIMI to function across any domain or subdomain.
Key findings
Subdomain precedence: The BIMI protocol allows mailbox providers to use a BIMI record found at a subdomain, even if it differs from a record published at the organizational domain.
Organizational domain application: The BIMI protocol is designed so that a record published at the organizational domain will apply to subdomains that do not have their own explicit BIMI record.
DMARC requirement: DMARC must be published on the organizational domain for BIMI to be published on either the organizational domain or its subdomains.
BIMI selector header: The BIMI specification defines a BIMI-Selector header that senders can insert into outbound mail to specify a particular BIMI record.
Key considerations
DMARC policy enforcement: To be eligible for BIMI, a domain must have DMARC deployed with an enforcement policy of p=quarantine or p=reject on its organizational domain. Find more details on BIMI Group's FAQ page.
DNS record format: The BIMI Assertion Record is stored as a DNS TXT record and must specify the location of the brand's SVG logo and an optional Verified Mark Certificate (VMC).
RFC compliance: Understanding RFC 5322 and other related RFCs is beneficial for correctly implementing BIMI and its dependencies like DMARC.
Multiple logos: BIMI selectors allow a domain to publish multiple BIMI records, each associated with a unique logo, offering brands flexibility in their visual representation.
Technical article
Documentation from BIMI Group FAQs clarifies that if a BIMI record is found at a subdomain, the mailbox provider is authorized to use it, even if it differs from the BIMI record published at the organizational domain.
20 Feb 2024 - BIMI Group FAQs
Technical article
Documentation from BIMI Group FAQs explains that the BIMI protocol is structured such that a record published at the organizational domain should automatically apply to any subdomains that do not have their own explicitly defined BIMI records.