technical · sourced answer
BIMI: Brand Indicators for Message Identification
BIMI is an email standard that allows organizations to display their brand logo next to their messages in supported email clients. It relies on a strict DMARC policy of quarantine or reject to ensure the sender is authenticated, preventing unauthorized parties from spoofing the brand logo.
Mechanical Operation
BIMI works by adding a specific TXT record to the DNS of a sending domain. This record contains a pointer to a publicly accessible SVG Tiny Portable Safe image file. When a receiving mail server sees the BIMI record, it first verifies that the email passed SPF and DKIM and that the domain has a DMARC policy set to p=quarantine or p=reject. If these conditions are met, the client fetches the SVG logo and displays it in the inbox.
Importance for Senders
BIMI increases brand visibility and trust by providing a visual cue of authenticity. Because it requires a high level of DMARC enforcement, it signals to the recipient that the email is legitimate. This can lead to higher open rates and a reduction in phishing attempts using the brand name, as only authenticated senders can trigger the logo display.
Operational Requirements
To implement BIMI, a sender must have a valid DMARC record with a policy of quarantine or reject. Many mailbox providers also require a Verified Mark Certificate (VMC), which is a digital certificate proving the organization owns the logo. Without a VMC, some providers may not display the logo even if the DNS records are correct. You can use SendHQ or its free tools (https://sendhq.cc/tools) to verify your DMARC status before attempting BIMI setup.
Common Implementation Mistakes
A frequent error is using a standard SVG file instead of the SVG Tiny Portable Safe profile, which causes the image to be rejected for security reasons. Another common mistake is setting a DMARC policy of p=none, which is insufficient for BIMI requirements. Senders also often forget to host the SVG file on a public HTTPS server that allows the mail client to fetch the asset without authentication.
Concrete Example
A company with the domain example.com creates a BIMI TXT record: default._bimi.example.com IN TXT "v=1; l=https://example.com/logo.svg". They ensure their DMARC record is v=DMARC1; p=reject; rua=mailto:dmarc@example.com. When they send an email, the recipient's mail client checks the DMARC policy, confirms the p=reject status, reads the BIMI record, and renders the logo.svg file in the user's inbox.
Questions teams ask
Does BIMI require DMARC?
Yes, BIMI requires a DMARC policy of either quarantine or reject. A policy of p=none is not sufficient for BIMI logo display.
What image format is required for BIMI?
BIMI requires the SVG Tiny Portable Safe (SVG P.S.) format to ensure the image does not contain malicious scripts.
Is a VMC mandatory for all BIMI users?
While the BIMI specification allows for it, most major mailbox providers require a Verified Mark Certificate (VMC) to display the logo.
Does BIMI improve email deliverability?
BIMI does not directly change the delivery path, but it improves trust and open rates by visually verifying the sender's identity.