When delving into Brand Indicators for Message Identification (BIMI), you often encounter various tags within the DNS record. Each tag serves a specific function in how your brand's logo is displayed in supporting email clients. Today, I want to clarify the purpose of a particular tag, the s= tag.
At its core, BIMI allows organizations to display a verified brand logo next to their sender information in the inbox, provided they have robust email authentication like DMARC in place. This visual cue helps recipients instantly recognize legitimate messages, building trust and improving engagement.
The s= tag, or selector tag, plays a crucial role in managing multiple BIMI records for a single domain. It allows you to specify different brand logos for various purposes, departments, or even for A/B testing, without requiring separate subdomains for each. This flexibility is key for larger organizations or those with diverse communication needs.
The purpose of the 's=' tag
Understanding BIMI selectors
The concept of a selector isn't unique to BIMI. We see similar mechanisms in DKIM records where the s= tag identifies a specific DKIM public key. In BIMI, the s= tag also acts as a unique identifier, but for a specific BIMI record. This allows you to differentiate between multiple BIMI records published for the same organizational domain.
Without the s= tag, you'd typically have one BIMI record per domain. This might be sufficient for smaller entities, but larger organizations often need more granularity. For instance, a company might want to display its primary corporate logo for general communications, but a different sub-brand logo for marketing campaigns or specific product lines.
The s= tag, often referred to as a BIMI selector, enables this flexibility. It allows a domain owner to publish multiple BIMI records, each with a unique selector, effectively creating different BIMI 'v=' tag values and associated BIMI 'l=' tag logo URLs.
Implementing BIMI with selectors
How the 's=' tag works for multiple logos
When you implement BIMI with selectors, you add the selector string (the value of the s= tag) to the beginning of your BIMI DNS record name. For example, if your selector is 'marketing', your BIMI record name might look like marketing._bimi.yourdomain.com. This specific record would then point to the logo intended for marketing communications.
Example BIMI TXT record with an 's=' tag (selector)DNS
marketing._bimi.yourdomain.com IN TXT "v=BIMI1; l=https://yourdomain.com/logos/marketing.svg; a=https://yourdomain.com/certificates/marketing.pem"
Email clients supporting BIMI will look for the s= tag in the email header to determine which specific BIMI record (and thus, which logo) to fetch from your DNS. This allows you to dynamically control the logo based on the email's context, sender, or campaign. You can learn more about this by reading how to implement BIMI selectors.
Key advantages of using BIMI selectors
Brand differentiation: Use distinct logos for different departments (e.g., sales, support, marketing) or sub-brands under one primary domain.
A/B testing: Experiment with different logo designs to see which resonates best with your audience and drives higher engagement.
Campaign specificity: Tailor the logo to specific campaigns or events, enhancing message relevance.
Streamlined management: Manage all your brand logos under a single domain, simplifying DNS administration.
Keep in mind that when using a selector, the BIMI record will be published as a TXT record in your DNS. Proper configuration is essential for your logos to display correctly. It's also important to remember the other BIMI tags, such as the h= tag, which is critical for indicating whether a Verified Mark Certificate (VMC) is required.
Advanced applications and future outlook
Considerations for effective selector usage
While selectors offer great flexibility, their effective use depends on a few factors. First, consistent email authentication across all sending sources is paramount. BIMI requires DMARC enforcement at a policy of quarantine or reject. Second, ensuring your SVG logo file meets BIMI compliance standards is crucial for proper rendering.
Furthermore, it's worth noting that not all email clients currently support BIMI, or its selector functionality. Adoption is growing, but it's important to verify which email clients support BIMI and how they handle multiple selectors. For organizations operating globally, this might mean a varied display experience across different regions and providers.
The 's=' tag in BIMI provides a powerful way to manage your brand's visual identity across different email touchpoints. It offers flexibility for branding, marketing, and even security, by clearly distinguishing communication types within a single domain. As BIMI continues to gain traction, leveraging selectors will become an increasingly important part of your email deliverability strategy.
Why the 's=' tag matters for your brand
Conclusion
The BIMI 's=' tag is more than just a technical detail, it's a strategic tool for brand management in the email space. By enabling the use of selectors, you can present a tailored visual identity for every type of communication, enhancing brand recognition and recipient trust. This flexibility is invaluable for maintaining a consistent and professional brand image.
To effectively implement and monitor BIMI, especially when utilizing selectors, robust DMARC monitoring is indispensable. DMARC ensures your email authentication is strong enough for BIMI to function, and provides crucial visibility into your email ecosystem.
For comprehensive DMARC monitoring and reporting, consider Suped. Our platform offers AI-powered recommendations to simplify complex DMARC data, real-time alerts for immediate issue detection, and a unified platform for DMARC, SPF, and DKIM. With our generous free plan, you can start optimizing your email security and deliverability today. Suped is designed to make DMARC accessible and actionable for businesses of all sizes, including MSPs.
