The Complete BIMI DNS Record

A BIMI (Brand Indicators for Message Identification) DNS record is a single TXT record that tells participating email clients where to find your brand logo and — when required — the certificate that proves you own it. Getting the syntax exactly right is non-negotiable: a single malformed tag causes silent failure with no bounce, no error log, and no logo.

This article covers every component of the BIMI TXT record, the rules governing each tag, the three canonical record configurations, and the misconfigurations that silently break logo display.

Prerequisites

Before publishing a BIMI record, confirm the following are in place:

1. DMARC policy is set to p=quarantine or p=reject with at least pct=100 (or equivalent enforcement).
2. Your logo file is in SVG Tiny P/S format and hosted at a publicly accessible HTTPS URL.
3. If targeting Gmail or Apple Mail, you have a valid VMC (Verified Mark Certificate) or CMC (Common Mark Certificate) in PEM format, also hosted at a publicly accessible HTTPS URL.

BIMI Record Structure

A BIMI TXT record follows this general syntax:

v=BIMI1; l=<logo-url>; a=<certificate-url>

| Tag | Name | Required | Description | |-----|------|----------|-------------| | v= | Version | Yes | Always BIMI1. | | l= | Logo URL | Yes | HTTPS URL pointing to your SVG Tiny P/S logo file. | | a= | Authority Evidence | Conditional | HTTPS URL pointing to your VMC or CMC in PEM format. Required for Gmail and Apple Mail. |

The record is published as a DNS TXT record at the following subdomain:

default._bimi.<yourdomain.com>

Note: The default selector is the standard selector used by all major email clients. Custom selectors are supported by the specification but are not yet widely implemented by receivers.

The l= Tag: Logo URL

What It Does

The l= tag provides the URL from which receiving mail clients fetch your brand logo. When a message passes DMARC alignment, the client retrieves this file and renders it alongside the sender name.

Requirements

• Protocol: Must be https://. HTTP URLs are rejected.
• Accessibility: The URL must be publicly accessible — no authentication, no redirects, no geo-blocking. Mail servers fetch this URL from their own infrastructure, not from a browser.
• File format: The file must conform to SVG Tiny P/S (Portable/Secure), a restricted subset of SVG 1.2 Tiny. Standard SVG files will fail validation even if they render correctly in a browser.
• Content-Type header: The server must return image/svg+xml.
• File size: Keep the file under 32 KB. Some receivers enforce stricter limits.

SVG Tiny P/S Key Restrictions

SVG Tiny P/S prohibits the following elements and attributes commonly found in standard SVG files:

• External references (, xlink:href pointing outside the file)
• Scripts (

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