What is a BIMI selector and how does it work?

A BIMI selector is a prefix in a BIMI DNS record that allows a domain to specify different brand logos for various email types. It works by having a unique TXT record for each selector, enabling mailbox providers to display the corresponding logo if it's referenced in the email header.

Which mailbox providers support BIMI selectors?

Most major BIMI-supporting mailbox providers, such as Gmail, Apple Mail, and Yahoo, primarily support the default BIMI selector. Support for custom, non-default selectors is limited and not consistently rendered across all email clients.

Do I need a Verified Mark Certificate (VMC) for each BIMI selector?

A Verified Mark Certificate (VMC) is generally tied to your domain and the specific logo you want to display. If you use different logos with different selectors, each logo typically needs to be included in your VMC, or you might need separate VMCs depending on the certificate issuer's policies and the complexity of your brand's digital assets.

How can I check if my BIMI selector is being recognized?

The most reliable way to check if your BIMI selector is being recognized is by sending an email and then inspecting the email headers in the recipient's inbox. Look for a BIMI-Selector header that specifies the selector you intended to use.

What is the primary prerequisite for BIMI implementation?

The primary prerequisite for BIMI implementation, including the use of selectors, is a strong DMARC policy set to enforcement (p=quarantine or p=reject). DMARC ensures that your emails are properly authenticated before a mailbox provider considers displaying your brand logo.

Do mailbox providers currently support BIMI selectors? - DMARC - Email authentication - Knowledge base

The question of whether mailbox providers currently support BIMI selectors is a nuanced one that many email senders encounter. While the concept of using selectors to display different brand logos based on email type or purpose is appealing, the reality of widespread support across all email clients is still evolving. We see varying levels of adoption and implementation, making it crucial to understand the current landscape.

Initially, the BIMI specification allowed for selectors, similar to how DKIM uses them to manage multiple keys. This design provides flexibility for brands that might want to use a distinct logo for transactional emails versus marketing campaigns, for example. However, simply publishing a BIMI record with a selector doesn't guarantee that a mailbox provider will honor it.

Most providers that support BIMI primarily recognize the default selector, which is implicitly used if no other selector is specified. Custom selectors, while technically possible to publish in your DNS, often receive limited or no rendering support from the major players. This situation creates a gap between the technical capability of BIMI and its practical application for advanced logo management.

What are BIMI selectors?

BIMI (Brand Indicators for Message Identification) selectors enable an organization to specify multiple BIMI records for a single domain. Each record can then point to a different brand logo. This is particularly useful for businesses that operate several brands under one primary domain or send various types of emails (e.g., transactional, promotional, or notification emails) each requiring a distinct visual identity.

A BIMI selector is essentially a prefix within the DNS record that differentiates one BIMI entry from another. If you're looking for a more in-depth explanation of how these selectors work, you can find a comprehensive guide on what the selector is for a BIMI record. It is published as a TXT record in your domain's DNS, typically on a subdomain like selector._bimi.yourdomain.com. This allows mailbox providers to look up the correct BIMI record based on the selector specified in the email's header.

For example, a brand might have a default logo for general correspondence and a 'transactional' logo for purchase confirmations. The DNS entry would reflect this by having two distinct BIMI records, one for the default and another for the transactional selector. Implementing BIMI involves specific requirements and implementation steps, including a valid DMARC policy and a Verified Mark Certificate (VMC) for certain providers.

Example BIMI record with a selectorDNS

transactional._bimi.yourdomain.com. IN TXT "v=BIMI1;l=https://cdn.yourdomain.com/transactional_logo.svg;a=https://www.digicert.com/vmc/yourdomain.pem;"

Mailbox providers and selector support

While many major mailbox providers have adopted BIMI, their support for selectors varies significantly. For instance,

Google's Gmail and

Apple Mail clients are known to support BIMI, which covers a large segment of the email user base, particularly for B2C organizations. However, their explicit support for non-default selectors is less consistent. You can explore the general landscape of which email clients support BIMI to get a broader understanding.

According to the official BIMI Group infographic, a number of providers are listed as supporting BIMI, including

Google,

Apple,

Yahoo, and

Fastmail. However, the same infographic notes that providers in the 'BIMI Planning' or 'Providers not supporting BIMI' categories may have other logo services available or have not shared support timelines. Notably, Microsoft (Exchange Online and Outlook) does not currently support BIMI rendering, which means logos from BIMI-compliant senders won't appear there. More details on Microsoft Outlook's BIMI support can be found in our knowledge base.

Mailbox Provider	General BIMI Support	Selector Support
Gmail	Yes	Primarily default; limited for others
Apple Mail (iOS, MacOS)	Yes	Primarily default; limited for others
Yahoo	Yes	Primarily default
Fastmail	Yes	Primarily default
Microsoft (Outlook, Exchange Online)	No	Not applicable
Onet Poczta, GMX, La Poste, AU, Cloudmark	Yes	Primarily default

While there have been examples of companies like Stripe using a 'transactional' selector and Amazon using a 'smile' selector in the past, their logos appeared on specific clients, such as iCloud. The broad adoption of these custom selectors by many mailbox providers to display different brand visuals has not yet become standard. Most providers still prioritize the single, default BIMI logo, emphasizing brand consistency above variation.

As of November 2024, the landscape indicates that while the BIMI standard is gaining traction, widespread support for BIMI selectors remains limited. Brands should focus on establishing a strong default BIMI record first, ensuring their primary logo displays consistently across supporting platforms, before investing heavily in multiple selectors.

The practical reality of BIMI selectors

The practical reality for brands looking to leverage BIMI selectors is that the technical capability exists, but consistent rendering across all supporting mailbox providers is not yet guaranteed. This means that while you can configure a BIMI record with a selector, its visibility will depend on the specific email client and its current implementation of the BIMI standard. The most reliable way to confirm if a selector is being honored is to inspect the email headers after delivery.

This situation underscores the importance of a robust email authentication strategy. DMARC is a prerequisite for BIMI, providing the foundational security that allows brand logos to be displayed. Without a properly configured DMARC policy, BIMI cannot function, regardless of selector support. Understanding the benefits of implementing DMARC is key to successful email branding and security.

Effective DMARC monitoring is crucial, especially when experimenting with advanced BIMI features like selectors. It helps you track authentication failures, identify unauthorized sending sources, and ensure your emails are consistently reaching the inbox. This continuous oversight is vital for maintaining a strong sender reputation and ensuring your brand's visual elements are correctly displayed.

Optimize your email authentication with

Suped's DMARC monitoring. Our platform offers comprehensive insights and features:

AI-Powered Recommendations: Get actionable advice to fix issues and strengthen your email policies.
Real-Time Alerts: Be instantly notified of any DMARC authentication failures or policy breaches.
Unified Platform: Monitor DMARC, SPF, and DKIM alongside blocklist and deliverability insights.
SPF Flattening: Simplify your SPF records to avoid DNS lookup limits and ensure compliance.
MSP and Multi-Tenancy Dashboard: Manage multiple domains efficiently from one centralized, user-friendly interface.

Views from the trenches

Best practices

Always prioritize setting up a strong DMARC policy before implementing BIMI selectors.

Use the default selector first and ensure it renders consistently across all major providers.

Regularly inspect email headers to verify if specific BIMI selectors are being recognized.

Keep your SVG logos simple and optimized for various display sizes across email clients.

Common pitfalls

Assuming all mailbox providers will support custom BIMI selectors immediately upon publication.

Neglecting DMARC monitoring, which is essential for BIMI authentication and deliverability.

Using complex SVG files that may not render correctly in all email environments.

Not verifying selector implementation through actual email delivery tests and header analysis.

Expert tips

Focus on establishing a solid, single brand identity with BIMI before trying complex selector strategies.

Utilize DMARC reports to identify any issues that might prevent BIMI logos from displaying.

Consider the impact of VMC requirements for your desired mailbox provider support levels.

Stay informed on the latest BIMI adoption trends among global mailbox providers and clients.

Marketer view

Marketer from Email Geeks says some mailbox providers do support BIMI selectors, as they developed to the specification, but sending platforms often lag in offering options to choose which selector to use.

2024-05-29 - Email Geeks

Marketer view

Marketer from Email Geeks recalls seeing Stripe's logo appear on iCloud when using a BIMI selector, indicating some level of support in certain clients.

2024-05-29 - Email Geeks

Navigating BIMI selectors

While the BIMI specification technically allows for the use of selectors, their practical support among mailbox providers is still quite limited. Most major providers like Gmail, Apple Mail, and Yahoo prioritize rendering the default BIMI logo, and custom selectors have not yet seen widespread adoption.

For brands, this means that while setting up a BIMI record with a selector is possible, you should temper expectations regarding its universal display. The focus should remain on solidifying your core email authentication with DMARC and ensuring your primary brand logo is correctly configured for maximum visibility. Monitoring your DMARC reports is essential to ensure your email authentication is performing as expected, especially when deploying advanced features like BIMI.

As the email ecosystem evolves, we may see more robust support for BIMI selectors. Until then, a pragmatic approach focusing on foundational authentication and consistent primary logo display will yield the best results for your brand's presence in the inbox.