Brand Indicators for Message Identification, or BIMI, is an email standard that allows you to display your brand's logo directly in your recipients' inboxes. The core idea, as Mailchimp notes, is to help customers avoid fraudulent emails by providing a verifiable visual cue. For BIMI to work, your domain must be authenticated with DMARC, ensuring that the emails are legitimately from you.
A basic BIMI setup involves publishing a single DNS record that points to your one official logo. However, the standard includes an often overlooked feature that provides much greater flexibility: the selector tag.
What is the 's=' tag in a BIMI record?
The s= tag in a BIMI record stands for 'selector'. A selector is an identifier that allows a domain owner to specify different logos for different email streams. Instead of having one logo for all emails sent from your domain, you can have many. You might have one for marketing, one for transactional emails, and another for a specific sub-brand.
When you use a selector, you aren't placing it in your default BIMI record. Instead, the selector becomes part of the DNS record's location itself. A standard default BIMI record is published at default._bimi.yourdomain.com. A record using a selector named 'marketing' would be published at marketing._bimi.yourdomain.com.
How do email clients use BIMI selectors?
For a receiving mail server to know which logo to look up, the sender must include a special header in the email. This is called the BIMI-Selector header. The value of this header tells the server which selector to use.
- An email is sent with a header like: BIMI-Selector: v=BIMI1; s=marketing;
- The recipient's mail system reads this header and identifies the selector is 'marketing'.
- It performs a DNS lookup for a TXT record at marketing._bimi.yourdomain.com.
- If a valid BIMI record is found, it uses the logo specified there.
- If no BIMI-Selector header is present, the system falls back to checking default._bimi.yourdomain.com for the domain's primary logo.
What are the main use cases for BIMI selectors?
The s= selector tag unlocks several powerful strategies for brand management in email. It gives you much more granular control over your brand's visual identity.
- Managing multiple brands or products: Large companies often operate different brands or services under a single parent domain. Selectors allow each brand to display its unique logo, creating a clear and consistent experience for customers.
- A/B testing logos: Wondering if a new logo design performs better? You can use selectors to send a portion of your emails with a new logo and compare engagement metrics like open rates against your standard logo.
- Seasonal and campaign-specific branding: Easily swap in a holiday-themed logo for a Christmas campaign or a special logo for a major product launch. This can be done without touching your primary, default BIMI record.
- Contextual logos: Use different logos for different types of communication. For example, a standard brand logo for marketing newsletters but a more functional logo (like one with a support icon) for customer service emails.
In short, the BIMI selector tag transforms BIMI from a simple, static feature into a dynamic branding tool. While not required for a basic implementation, it provides a level of control that is essential for any complex organization or savvy marketer looking to get the most out of their email presence.
