BIMI (Brand Indicators for Message Identification) displays your brand logo next to your email in the recipient's inbox — in Gmail, Yahoo Mail, Apple Mail, and other supporting clients. It is the visible reward for implementing DMARC enforcement: once your domain reaches p=quarantine or p=reject, you become eligible to publish a BIMI record and have your logo appear alongside your messages. Studies from participating senders show open rate lifts of 4–6% from BIMI logo display alone — a significant return for a one-time infrastructure change.
Prerequisites Before Publishing Your BIMI Record
BIMI requires a complete authentication stack to function. Publishing a BIMI record without meeting every prerequisite results in the logo not appearing — there is no error message; the mailbox provider simply ignores the BIMI record silently. Verify each prerequisite before attempting configuration.
| Prerequisite | Requirement | How to verify | Status check |
|---|---|---|---|
| SPF | Valid record, passes for all sending sources | MXToolbox SPF check | Must show spf=pass in Authentication-Results |
| DKIM | 2048-bit key signing all outbound mail | mail-tester.com | dkim=pass, d= matches From: domain |
| DMARC | p=quarantine or p=reject, pct=100 | MXToolbox DMARC | dmarc=pass; p=none disqualifies BIMI |
| Logo format | SVG Tiny Portable/Secure (SVG-P/S), square, ≤32 KB | BIMI Group Inspector | bimigroup.org/bimi-generator |
| Logo hosting | Hosted at HTTPS URL on your domain | curl -I your-logo-url | Must return 200 with valid SVG content-type |
| Mark Certificate | VMC or CMC for Gmail; self-asserted OK for Yahoo | CA issuance email | PEM file hosted at HTTPS URL |
VMC vs CMC vs Self-Asserted — Which Do You Need?
The certificate requirement is the most confusing part of BIMI because it differs by mailbox provider. Yahoo and some smaller providers display your logo without any certificate — a self-asserted BIMI record is sufficient. Gmail requires either a Verified Mark Certificate (VMC) or a Common Mark Certificate (CMC). Apple Mail uses Apple Business Connect, which is separate from BIMI entirely.
BIMI Certificate Requirements by Mailbox Provider (2025)
| Provider | Self-asserted | CMC required? | VMC required? | Blue checkmark? |
|---|---|---|---|---|
| Yahoo Mail / AOL | Yes — logo displays | No (optional) | No (optional) | No |
| Gmail | No — ignored | Yes — logo displays | Yes — logo + checkmark | VMC only |
| Apple Mail | Apple Business Connect (separate) | N/A | N/A | No |
| Fastmail | Yes — logo displays | No | No | No |
| Outlook / Microsoft 365 | Limited — testing | TBC | TBC | No (yet) |
The difference between VMC and CMC: a VMC requires your logo to be a registered trademark with one of 17 recognized intellectual property offices (USPTO, EUIPO, UKIPO, etc.). A CMC does not require trademark registration — it verifies logo ownership and domain association without the trademark requirement. Both are issued by DigiCert or Entrust. VMCs trigger Gmail's blue verification checkmark; CMCs display the logo without the checkmark.
Publishing the BIMI DNS Record
The BIMI record is a TXT record published at default._bimi.yourdomain.com. It contains two fields: l= (the URL of your SVG logo) and a= (the URL of your PEM certificate file — required for Gmail). For Yahoo-only BIMI without a certificate, the a= field is omitted.
# Self-asserted BIMI — works for Yahoo, Fastmail (not Gmail) default._bimi.yourdomain.com IN TXT "v=BIMI1; l=https://images.yourdomain.com/logo/bimi-logo.svg;" # Certified BIMI — required for Gmail (VMC or CMC) default._bimi.yourdomain.com IN TXT "v=BIMI1; l=https://images.yourdomain.com/logo/bimi-logo.svg; a=https://images.yourdomain.com/logo/bimi-certificate.pem" # Verify the record after publishing (propagation up to 48h): $ dig TXT default._bimi.yourdomain.com +short "v=BIMI1; l=https://images.yourdomain.com/logo/bimi-logo.svg; a=https://images..." # Test with BIMI Group Inspector: # https://bimigroup.org/bimi-generator/ # Enter your domain and it will check DMARC, logo, certificate, and record format
SVG Logo — Format Requirements
The most common BIMI implementation failure is logo format. Standard SVG files exported from Illustrator or Figma do not meet BIMI's SVG Tiny Portable/Secure (SVG-P/S) profile requirement. The SVG must be square (1:1 aspect ratio), have no transparent background, be under 32 KB, and conform to the SVG Tiny 1.2 profile with specific namespace requirements.
<?xml version="1.0" encoding="UTF-8"?>
<svg xmlns="http://www.w3.org/2000/svg"
xmlns:xlink="http://www.w3.org/1999/xlink"
version="1.2"
baseProfile="tiny-ps"
viewBox="0 0 100 100">
<!-- Logo content here -->
<!-- No JavaScript, no external references, no filters -->
<!-- Background must be non-transparent -->
<rect width="100" height="100" fill="#ffffff"/>
<!-- Your logo paths here -->
</svg>
# Key requirements:
# version="1.2" and baseProfile="tiny-ps" are MANDATORY
# Square viewport (viewBox width == height)
# Non-transparent background (white or brand color rect covering full canvas)
# No external resources, scripts, or animations
# File size must be under 32 KB
# Validate at: https://bimigroup.org/bimi-generator/
▶ BIMI implementation — step-by-step deployment
curl -I returns HTTP 200 with content-type: image/svg+xml.BIMI Troubleshooting — Why Your Logo Is Not Appearing
After publishing the BIMI record, logos typically appear within 24–48 hours in Yahoo and 48–72 hours in Gmail. If your logo is not appearing after 72 hours, work through this checklist in order. The BIMI Group Inspector at bimigroup.org provides a diagnostic report that covers most common failures.
| Symptom | Likely cause | Fix |
|---|---|---|
| Logo shows in Yahoo, not Gmail | Certificate missing or invalid | Add VMC or CMC PEM file to a= field |
| Logo not showing anywhere | DMARC not at enforcement or pct < 100 | Move DMARC to p=quarantine pct=100 minimum |
| BIMI Group Inspector shows logo error | SVG format not SVG Tiny-PS | Re-export and validate SVG profile headers |
| Certificate error in inspector | PEM chain incomplete or HTTP URL | Append intermediate CA certs; confirm HTTPS |
| Logo appears but distorted | Non-square viewBox or transparency | Set equal width/height, add opaque background |
Situation: BIMI record published, logo appeared in Yahoo within 24 hours. Never appeared in Gmail after 3 weeks. DMARC at p=reject, pct=100.
Diagnosis: BIMI Group Inspector showed: "Certificate not found at a= URL — HTTP 404". The PEM file had been uploaded to the correct server but with a typo in the filename in the DNS record.
Fix: Corrected the PEM URL in the BIMI TXT record. GMail logo appeared within 48 hours after DNS propagation. Also discovered the SVG had a transparent background — replaced with white rect to meet SVG-P/S profile. Blue verification checkmark appeared in Gmail after VMC validation completed.
