The short answer is no, BIMI (Brand Indicators for Message Identification) does not have a built-in fallback mechanism for email clients that do not support it. Instead, if a recipient's email client doesn't support BIMI, it simply will not display your logo. The email will render according to that specific client's default behavior, which usually means showing a generic avatar or the sender's initials.
BIMI is designed as an enhancement, not a fundamental component of an email. Its purpose is to add a layer of visual verification and branding for recipients using a supported mail client. As the BIMI Group states, it's an emerging email specification that builds upon strong email authentication.
Because BIMI builds on top of DMARC, you first need to have DMARC correctly configured and at enforcement before you can even think about implementing BIMI.
What unsupported clients see
When an email is delivered to a client that doesn't support BIMI, the system doesn't look for or process the BIMI DNS record. As a result, the recipient will see the default display that the email client provides for all senders who don't have a logo configured through other means (like a Google Profile for Gmail users).
This typically includes:
- Generic initials: A colored circle with the first letter of the sender's name (e.g., 'S' for Suped).
- A generic icon: A placeholder silhouette or icon.
- Nothing at all: Simply empty space where a logo might otherwise appear.
The key is that the email itself is not negatively affected. Deliverability isn't harmed, and the message content is displayed as intended. The absence of a logo is the only difference.
How this differs from a true fallback
To understand why this isn't considered a 'fallback', it's helpful to look at a technology that does require one: AMP for Email. AMP allows for interactive elements within an email, but not all clients can render them.
As Mailgun points out, senders using AMP must include a standard HTML version of their email. This is a true fallback. Email clients that don't support AMP will display the HTML version, ensuring all users get a functional email. BIMI has no such requirement because its absence doesn't break the email's functionality.
The importance of DMARC enforcement
It's impossible to discuss BIMI without mentioning DMARC. BIMI is not just about placing a logo; it's a reward for senders who have implemented strong email authentication to prevent phishing and spoofing. To qualify for BIMI, your domain must have a DMARC policy at enforcement, meaning a policy of p=quarantine or p=reject.
This prerequisite ensures that only legitimate senders can display their logos, making it a trustworthy signal for recipients. The lack of a logo in an unsupported client is simply the status quo, whereas the presence of one in a supported client is a sign of enhanced security and brand authenticity.
Conclusion
To summarize, BIMI does not provide a specific fallback for unsupported email clients. It is an enhancement that works only where it is supported. In clients that do not support it, your email simply appears as it normally would, without any negative impact. The real 'fallback' is the email client's own default rendering, ensuring your message always gets through, logo or not.
