When you send an email, you want recipients to instantly recognize your brand. Brand Indicators for Message Identification, or BIMI, helps make that happen by displaying your logo right next to your email in the inbox. This visual verification builds trust and helps your messages stand out in a crowded inbox.
At the heart of a BIMI record, which is a DNS TXT record, are various tags that define its behavior and content. One of the most crucial of these is the l= tag, which directly points to the location of your brand's logo file. Without it, your logo simply cannot be displayed.
Understanding the function of the l= tag is fundamental for anyone looking to successfully implement BIMI. It's not just about pointing to an image, it's about ensuring that image is correctly formatted, securely hosted, and accessible to email providers worldwide. Let's delve into its specific purpose and requirements.
The role of the 'l=' tag
Specifying the logo location
The primary purpose of the BIMI l= tag is to provide a direct URL to your brand's official logo file. This URL tells participating email clients, such as Google and Yahoo, where to fetch the logo that should be displayed alongside your authenticated emails. Think of it as a signpost that guides email systems to your visual brand asset.
For the l= tag to function correctly, the URL must point to a specific type of image file: a Scalable Vector Graphics (SVG) Tiny Portable/Secure (SVG P/S) file. This format is crucial for security and scalability, ensuring that your logo looks crisp and clear on any device or screen size. The URL specified in the l= tag must also be served over HTTPS, adding an essential layer of security to prevent tampering or unauthorized access to your logo.
Example BIMI record with 'l=' tagDNS TXT
default._bimi.yourdomain.com IN TXT "v=BIMI1; l=https://yourdomain.com/bimi/logo.svg; a=https://yourdomain.com/bimi/vmc.pem;"
The requirement for HTTPS not only protects the integrity of your logo but also aligns with modern web security best practices. Email providers expect a secure connection when fetching sensitive brand assets, further reducing the risk of phishing attacks where malicious actors might try to impersonate your brand by displaying a fake logo. The l= tag, therefore, plays a dual role of both location identifier and security enforcer.
SVG requirements and security considerations
SVG requirements and security considerations
The strict requirements for the SVG file linked in the l= tag are in place for several reasons, primarily security and consistent rendering. The SVG Tiny P/S format is a constrained version of SVG that limits potentially malicious elements, preventing your logo file from being exploited to carry out attacks through email clients. For more details, refer to the BIMI Group Blog.
Accessibility: It needs to be publicly accessible, meaning no password protection or restricted access. Email clients need to be able to retrieve it freely.
Size: While SVG is vector-based, keeping the file size optimized is still a good practice for faster loading.
Beyond the technical specifications, the security around your logo's hosting is paramount. If a bad actor were able to compromise the server hosting your SVG file, they could potentially replace your legitimate logo with a fraudulent one, leading to brand impersonation. This is why email providers place such a strong emphasis on the secure hosting of your BIMI assets.
The l= tag is complemented by the BIMI a= tag, which points to your Verified Mark Certificate (VMC). The VMC cryptographically binds your logo to your authenticated domain, providing an additional layer of assurance that the logo displayed is indeed yours. This combination ensures both visual consistency and verifiable authenticity.
Impact on brand identity and trust
Impact on brand identity and trust
The visual display of your logo, facilitated by the l= tag, has a profound impact on brand identity and recipient trust. When subscribers see your familiar logo in their inbox, it creates instant recognition and reinforces your brand presence. This can lead to increased open rates and engagement because recipients are more likely to trust emails that clearly display their sender's identity.
In a digital landscape rife with phishing and spoofing attempts, BIMI provides a powerful visual cue that an email is legitimate. The presence of your logo, verified by DMARC and a VMC, signals to recipients that the sender has taken steps to secure their email communications. This directly addresses the concerns mentioned in Knak's blog post about BIMI, highlighting its role in exemplifying trust and security to customers.
This enhanced trust isn't just a feel-good factor, it translates into tangible benefits for your email deliverability and overall marketing efforts. Emails with a verified logo are less likely to be marked as spam or ignored, improving your sender reputation. For a deeper dive into the broader advantages, explore the value of BIMI and its impact.
Implementation and monitoring
Implementation and monitoring
Implementing BIMI involves more than just setting the l= tag. It requires your domain to have a DMARC policy enforced at quarantine or reject, and typically involves a VMC, specified by the a= tag. The BIMI record itself starts with the v= tag, always set to BIMI1. Ensuring that your SVG and VMC are correctly configured and valid is crucial for successful deployment. There are tools available to validate your BIMI SVG and certificate.
BIMI record tags
v=: The BIMI version tag, always BIMI1.
l=: The URL to your brand's SVG logo file.
a=: The URL to your Verified Mark Certificate (VMC) file, if used.
s=: Indicates whether the VMC is self-signed or from a Certificate Authority.
Key DMARC policy settings
p=: Specifies the policy for non-aligned emails: none, quarantine, or reject.
pct=: Percentage of emails to which the policy applies.
rua=: Aggregate DMARC reports recipient address.
ruf=: Forensic DMARC reports recipient address.
Once BIMI is implemented, continuous monitoring is key. DMARC reports will show you if your emails are authenticating correctly and if your BIMI logo is being displayed as intended. These reports offer invaluable insights into potential issues with your configuration, including those related to the l= tag or your SVG file. Platforms like Suped provide detailed DMARC reporting and monitoring, helping you easily track and troubleshoot your BIMI implementation.
Effective DMARC monitoring is essential not only for BIMI but for your overall email security posture. It allows you to gain visibility into your email ecosystem, detect unauthorized senders, and ensure consistent brand representation. By actively monitoring your DMARC records, you can quickly identify and resolve any issues that might prevent your logo from appearing or impact your email deliverability. Suped's list of DMARC tags and their meanings can help you understand all the components of your DMARC record.
Summary of the 'l=' tag's importance
Conclusion
The BIMI l= tag is a small but mighty component of your email authentication strategy. It serves as the bridge between your brand's visual identity and your secure email communications, ensuring that your logo is accurately and securely displayed in recipient inboxes. Proper configuration of this tag, along with adherence to SVG requirements and a robust DMARC policy, is essential for leveraging BIMI to its full potential, enhancing brand recognition, and fostering recipient trust.
Google and Yahoo, where to fetch the logo that should be displayed alongside your authenticated emails. Think of it as a signpost that guides email systems to your visual brand asset.
