BIMI, or Brand Indicators for Message Identification, is an email standard that allows you to display your company's logo next to your messages in your recipient's inbox. It's a great way to improve brand recognition and trust. To make BIMI work, you publish a special DNS record. This record contains various pieces of information called 'tags', and one of these is the l= tag.
The l= tag, which stands for 'logo', is an optional but powerful part of a BIMI DNS record. Its primary purpose is to specify the direct URL of your brand's logo file, which must be in SVG format. While not always required, it plays a key role when using a feature known as BIMI Selectors.
How the 'l=' tag works with BIMI selectors
In a standard, default BIMI setup, you typically have one logo for your entire domain. The location of this logo is usually embedded within your Verified Mark Certificate (VMC), which is specified by the a= (authority) tag. You don't need the l= tag in this scenario.
However, what if you want to use different logos for different types of emails? For example, a special logo for a holiday campaign or different logos for your transactional emails versus your marketing newsletters. This is where BIMI Selectors come in, and the l= tag becomes essential.
A selector is just a name you choose, like 'marketing' or 'holidays2024'. You then create a specific BIMI record for that selector, such as marketing._bimi.yourdomain.com. In this selector-specific DNS record, you use the l= tag to point directly to the alternative logo's URL. When you send an email, you include a BIMI-Selector header that specifies which selector to use.
Example BIMI records
- Default Record (no 'l=' tag): v=BIMI1; a=https://path/to/your/vmc.pem; In this case, the email client finds the logo URL inside the VMC file.
- Selector Record (with 'l=' tag): v=BIMI1; l=https://path/to/your/special-logo.svg; This record would live at selector-name._bimi.yourdomain.com. The l= tag explicitly tells the email client where to find the logo for this specific selector.
According to the official BIMI Group website, this allows for significant flexibility. It means you are not locked into a single logo tied to your VMC. You can have a VMC that covers your primary trademarked logo, but still use selectors with the l= tag for non-trademarked, campaign-specific logos.
Conclusion
In short, the purpose of the BIMI l= tag is to provide flexibility for your brand's visual identity in the inbox. It is the mechanism that powers BIMI Selectors, allowing a single domain to use multiple logos for different email campaigns or streams. By using the l= tag, you can tailor your branding for specific audiences and contexts, making your email presence more dynamic and effective.
