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Does BIMI trickle down to subdomains and how to control subdomain BIMI display?

7 Marketer opinions3 Expert opinions3 Technical articles1 Resource

Summary

BIMI's behavior in subdomains is fundamentally governed by DMARC policies. While DMARC policies are inherited from the parent domain, specific DMARC records at the subdomain level are essential for controlling BIMI display. These records can either enforce the parent domain's BIMI, override it, or disable BIMI altogether. Key methods for controlling BIMI include ensuring DMARC compliance, implementing specific DMARC policies (reject/quarantine), utilizing non-functional BIMI records (e.g., `v=BIMI1;`), and aligning the subdomain's DMARC record with the sending domain. Without explicit DMARC configurations, subdomains default to the parent domain's settings, potentially leading to unintended BIMI displays.

Key findings

  • DMARC's Role: BIMI relies heavily on valid DMARC policies for proper functioning in subdomains.
  • Inheritance and Overriding: Subdomains inherit DMARC policies, but this inheritance can be overridden with subdomain-specific DMARC records.
  • Subdomain Specificity: Controlling BIMI on a subdomain requires implementing a DMARC record directly on that subdomain.
  • Disabling BIMI: A non-functional BIMI record (v=BIMI1;) can be used to prevent logo display on a subdomain.
  • DMARC Compliance: To effectively enable BIMI, subdomains need to be DMARC compliant, often requiring 'reject' or 'quarantine' policies.

Key considerations

  • DMARC Configuration: Carefully configure DMARC records on each subdomain to achieve desired BIMI behavior.
  • Enforcement Level: Ensure DMARC policies are enforced (beyond 'p=none') for BIMI to function as expected.
  • Alignment: Verify that the subdomain's DMARC record is aligned with the sending domain for optimal BIMI performance.
  • Hierarchical Understanding: Understand how DMARC policies cascade from parent domains to subdomains to avoid unintended consequences.
  • Testing and Validation: Thoroughly test and validate BIMI configurations across various subdomains and email clients.

What email marketers say
7Marketer opinions

BIMI behavior on subdomains is governed by DMARC policies. Subdomains inherit the parent domain's DMARC policy unless specifically overridden with their own DMARC record. To control BIMI display on subdomains, implementing specific DMARC records is necessary. This can be achieved by setting a DMARC policy of 'reject' or 'quarantine' on the subdomain, ensuring DMARC alignment with the sending domain, or using a non-functional BIMI record (e.g., `v=BIMI1;`) to disable the logo. Without a specific DMARC record, the subdomain will inherit the parent domain's BIMI settings.

Key opinions

  • DMARC Inheritance: Subdomains inherit the DMARC policy from the parent domain by default.
  • Subdomain Override: To control BIMI on a subdomain, you must create a specific DMARC record for that subdomain.
  • BIMI Disable: Setting a non-functional BIMI record (v=BIMI1;) on a subdomain can prevent the BIMI logo from displaying.
  • DMARC Requirement: Subdomains must have a DMARC policy of 'reject' or 'quarantine' for BIMI to function correctly in some cases.
  • DMARC Alignment: Valid DMARC alignment on the subdomain is crucial for BIMI to work as intended.

Key considerations

  • DMARC Configuration: Properly configure DMARC records on subdomains to manage BIMI display effectively.
  • Granular Control: Implement specific DMARC policies for each subdomain to achieve granular control over BIMI branding.
  • Subdomain Strategy: Consider your subdomain strategy and how BIMI aligns with each subdomain's purpose.
  • Testing: Thoroughly test BIMI implementation across different subdomains and email clients to ensure consistent branding.
Marketer view

Email marketer from Mailhardener.com explains the hierarchical nature of DMARC and its effect on BIMI. Subdomains inherit the DMARC policy of the main domain unless overridden. Therefore, BIMI's effect on subdomains is tied to the DMARC policy in place. To disable BIMI on subdomains, setting a specific DMARC record is necessary.

July 2023 - Mailhardener.com
Marketer view

Email marketer from EmailToolTester.com explains that subdomains need a DMARC policy of 'reject' or 'quarantine' for BIMI to work correctly. If a subdomain uses 'none' or lacks a DMARC record, BIMI may not display.

May 2023 - EmailToolTester.com
Marketer view

Email marketer from Gmass.co explains that the best way to ensure BIMI displays correctly on subdomains is to create specific DMARC records on each subdomain. This overrides and enables control of BIMI on each subdomain.

September 2023 - Gmass.co
Marketer view

Email marketer from StackOverflow suggests that to prevent a subdomain from displaying a BIMI logo, you can set the BIMI record on that specific subdomain to an empty or non-functional BIMI record (e.g., `v=BIMI1;`). This overrides the parent domain's BIMI setting.

February 2024 - StackOverflow
Marketer view

Marketer from Email Geeks shares a method to prevent BIMI logos from showing on subdomains. Setting the BIMI record to `v=BIMI1;` will disable the logo display for that subdomain.

November 2024 - Email Geeks
Marketer view

Email marketer from LinkedIn recommends implementing a specific DMARC policy for each subdomain if you want granular control over BIMI. This ensures that only intended subdomains display the BIMI logo.

April 2024 - LinkedIn
Marketer view

Email marketer from Reddit states that for BIMI to work on a subdomain, the subdomain needs a valid DMARC record aligned with the sending domain. If the subdomain doesn't have a DMARC record or the alignment fails, BIMI won't be displayed.

April 2024 - Reddit

What the experts say
3Expert opinions

Controlling BIMI display on subdomains hinges on properly configured DMARC records. While DMARC policies are inherited, subdomains require their own specific DMARC records to manage BIMI independently from the parent domain. To effectively manage BIMI display and override parent domain settings, it's essential to ensure DMARC compliance and enforcement on each subdomain.

Key opinions

  • DMARC Enforcement: BIMI requires DMARC compliance at the subdomain level, implying settings beyond just 'p=reject; sp=none'.
  • DMARC Inheritance & Override: While DMARC policies are inherited, controlling BIMI necessitates specific DMARC records on each subdomain.
  • Subdomain DMARC Requirement: To prevent a subdomain from using the top-level domain's BIMI, a DMARC record must exist on each subdomain.

Key considerations

  • Subdomain Compliance: Ensure each subdomain is DMARC compliant to fully leverage BIMI.
  • Specific DMARC Records: Implement specific DMARC records for each subdomain where BIMI needs to be managed separately.
  • Override Strategy: Plan a strategy for overriding inherited DMARC policies on subdomains where necessary.
Expert view

Expert from Spam Resource explains that while DMARC policies are inherited by subdomains, controlling BIMI display requires specific DMARC records for each subdomain. A subdomain without a DMARC record will inherit the parent's policy, but to disable BIMI, the subdomain must have its own DMARC record.

May 2024 - Spam Resource
Expert view

Expert from Word to the Wise details how to manage BIMI in subdomains. Because BIMI relies on the DMARC policy to function correctly, to prevent a subdomain from using the top level domain's BIMI, a DMARC record must exist on each subdomain.

January 2025 - Word to the Wise
Expert view

Expert from Email Geeks explains that for BIMI to work on subdomains, the subdomain needs to be compliant with DMARC at enforcement, meaning settings like `p=reject; sp=none` are not sufficient.

November 2023 - Email Geeks

What the documentation says
3Technical articles

BIMI's behavior on subdomains is intrinsically linked to DMARC policies. DMARC policies are inherited by subdomains, and to manage BIMI at the subdomain level, specific DMARC records need to be implemented. The presence and configuration of these subdomain DMARC records determine whether the top-level BIMI record influences the subdomain's branding.

Key findings

  • DMARC Dependency: BIMI relies on a valid DMARC policy to function, both at the top level and subdomain level.
  • DMARC Inheritance: Subdomains inherit DMARC policies from the parent domain.
  • Subdomain Control: Specific DMARC records are necessary at the subdomain level to control BIMI display.

Key considerations

  • DMARC Validation: Ensure DMARC policies at the subdomain level pass validation for BIMI to function.
  • Policy Configuration: Properly configure DMARC records to dictate whether BIMI applies to a given subdomain.
  • Hierarchical Management: Understand the hierarchical nature of DMARC policies when managing BIMI across different subdomains.
Technical article

Documentation from dmarc.org details how DMARC policies are inherited by subdomains. To control BIMI at the subdomain level, specific DMARC records need to be in place for the subdomain. If the subdomain has its own DMARC policy, it will dictate whether BIMI applies.

July 2022 - dmarc.org
Technical article

Documentation from Entrust.com clarifies that BIMI relies on a valid DMARC policy. Subdomains inherit DMARC policies, influencing BIMI display. Properly configured DMARC records at the subdomain level are necessary for BIMI to function correctly.

June 2021 - Entrust.com
Technical article

Documentation from DigiCert.com explains that BIMI, like DMARC, can apply to subdomains. The behavior depends on the DMARC policy set for the subdomain. If a subdomain has a DMARC policy that passes validation, the BIMI record at the top level can influence the subdomain's branding.

April 2022 - DigiCert.com

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