BIMI Syntax Validator

Why validate BIMI syntax before publication?

A malformed BIMI record or non-compliant logo is silently ignored by webmail clients. Gmail, Yahoo, Apple Mail: none will alert you that your brand isn't displaying. Your emails arrive without the trust logo you expected.

The BIMI syntax validator analyzes your record before DNS publication. It downloads the logo, verifies Tiny-PS compliance and inspects the VMC. You detect errors immediately.

Common issues detected:

Invalid v= tag → Record not recognized as BIMI
Non-compliant Tiny-PS logo → Rejected by webmail clients
Expired or invalid VMC → Logo not displayed even if record is correct
Non-HTTPS URL → Automatic rejection per BIMI specifications

How to validate your BIMI record in 3 steps

Step 1: Prepare the BIMI record

Prepare your complete BIMI record. Standard structure:

v=BIMI1; l=https://brand.captaindns.com/logo.svg; a=https://brand.captaindns.com/vmc.pem

Components:

v=BIMI1 → Protocol version (required)
l= → HTTPS URL of Tiny-PS compliant SVG logo (required)
a= → HTTPS URL of VMC certificate (optional but recommended)

Step 2: Paste and validate

Paste the record into the field above. The tool:

Parses v, l, a tags
Downloads the SVG logo from the specified URL
Analyzes Tiny-PS compliance
Downloads and inspects VMC if present
Generates a comprehensive report with status per element

Step 3: Fix and publish

The diagnostic shows for each element:

✅ Valid → Ready for publication
❌ Error → Correction required before publication
⚠️ Warning → Functional but improvement recommended

Fix errors, validate again, then publish to default._bimi.yourdomain.com.

What is BIMI?

BIMI (Brand Indicators for Message Identification) displays your brand logo in recipients' inboxes. When your emails pass DMARC authentication, compatible webmail clients retrieve and display your logo.

BIMI prerequisites:

DMARC configured with quarantine or reject policy
SPF and DKIM properly aligned
SVG logo compliant with Tiny-PS profile
VMC (optional but required by Gmail/Yahoo/Apple Mail)

Example BIMI record:

v=BIMI1; l=https://cdn.captaindns.com/bimi/logo.svg; a=https://cdn.captaindns.com/bimi/vmc.pem

The record is published as TXT on default._bimi.yourdomain.com.

BIMI tag validation details

Tags and accepted values

Tag	Required	Description
v	Yes	Protocol version. Only valid value: `BIMI1`
l	Yes	HTTPS URL of Tiny-PS compliant SVG logo
a	No	HTTPS URL of VMC (Verified Mark Certificate)

URL constraints

HTTPS protocol required (HTTP rejected)
No redirects to different domains
Correct Content-Type (image/svg+xml for logo, application/pkix-cert for VMC)
Public accessibility without authentication

SVG Tiny-PS logo validation

Tiny-PS profile requirements

The SVG logo must comply with the SVG Tiny Portable/Secure profile defined by BIMI:

Criterion	Requirement
Format	SVG (not PNG, JPEG, WebP)
viewBox	Present and square (e.g., `viewBox="0 0 100 100"`)
width/height	Absent or equal
Scripts	Prohibited (no `<script>`, `onclick`, etc.)
External references	Prohibited (no `<image href="...">`, `<use>`)
foreignObject	Prohibited
External fonts	Prohibited
Raster data URIs	Prohibited

Common logo errors

Error code	Cause	Solution
`BIMI_LOGO_NOT_SVG`	File is not SVG	Convert to vector SVG
`BIMI_LOGO_NOT_TINYPS`	Logo not Tiny-PS compliant	Remove scripts, external refs
`BIMI_LOGO_URL_INVALID`	Malformed or non-HTTPS URL	Fix URL with https://
`BIMI_LOGO_REDIRECT`	Redirect detected	Use direct final URL
`BIMI_LOGO_DATA_URI`	Data URI instead of URL	Host logo on a server

VMC certificate validation

What the tool checks

Check	Description
Accessibility	Certificate is downloadable
PEM format	Valid certificate structure
Validity dates	Not expired, not yet revoked
Issuing authority	Recognized CA (DigiCert, Entrust)
Domain consistency	Certificate covers the BIMI domain

Common VMC errors

Error code	Cause	Solution
`BIMI_VMC_URL_INVALID`	Inaccessible or malformed URL	Check VMC hosting
`BIMI_VMC_EXPIRED`	Expired certificate	Renew with CA
`BIMI_VMC_UNTRUSTED_CA`	Unrecognized CA	Use DigiCert or Entrust
`BIMI_VMC_LOGO_MISMATCH`	VMC logo ≠ BIMI logo	Use same logo everywhere

DMARC prerequisites for BIMI

BIMI only works if DMARC is properly configured:

Requirement	Detail
DMARC record	Present at `_dmarc.yourdomain.com`
Policy	`p=quarantine` or `p=reject` (not `none`)
SPF alignment	From address matches SPF domain
DKIM alignment	From address matches DKIM domain

Important: With p=none, webmail clients ignore BIMI even if the record is perfect.

BIMI deployment best practices

1. Prepare the logo correctly

<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100">
  <!-- Simple vector logo, no scripts, no external refs -->
  <circle cx="50" cy="50" r="45" fill="#4F46E5"/>
  <text x="50" y="60" text-anchor="middle" fill="white" font-size="24">B</text>
</svg>

Logo checklist:

2. Host on reliable CDN

Stable, permanent URL
HTTPS with valid certificate
No redirects
Content-Type: image/svg+xml
Long cache (logo rarely changes)

3. Configure DMARC before BIMI

Recommended progression:

SPF + DKIM configured and functional
DMARC p=none → Monitor reports
DMARC p=quarantine → Test progressively
DMARC p=reject → Maximum protection
BIMI → Logo visible after DMARC enforced

4. VMC for major brands

VMC is essential for Gmail, Yahoo and Apple Mail. Process:

Trademark registered with recognized office
VMC request from DigiCert or Entrust
Identity and trademark ownership verification
Certificate issuance (2-4 weeks)
Hosting and reference in a= tag

FAQ - Frequently asked questions

Q: Which BIMI tags are required?

A: Two tags are required: v=BIMI1 (version) and l= (logo URL). The a= tag (VMC) is optional but required by Gmail, Yahoo and Apple Mail to display the logo.

Q: What is the SVG Tiny-PS profile?

A: Tiny-PS (Tiny Portable/Secure) is a secure SVG subset required by BIMI. It prohibits:

JavaScript scripts
<foreignObject> elements
External fonts
References to external resources
Data URIs containing raster images

Q: Why is my SVG logo rejected?

A: Common causes:

PNG/JPEG format instead of vector SVG
JavaScript scripts or events present
References to external images or fonts
Missing or non-square viewBox
Incorrect Content-Type on server (image/svg+xml required)

Q: Is the VMC certificate mandatory?

A: Technically no, but in practice yes. Gmail, Yahoo and Apple Mail (which represent the majority of email inboxes) require a valid VMC to display the BIMI logo.

Q: How do I get a VMC certificate?

A: VMCs are issued by certified authorities (DigiCert, Entrust). You must:

Own a trademark registered with a recognized office
Prove ownership of that trademark
Pass the CA's identity verification

Cost: approximately $1,000-1,500/year. Timeline: 2-4 weeks.

Q: Why validate before DNS publication?

A: Webmail clients silently ignore invalid BIMI records. You receive no alert, but your logo doesn't display. Pre-validation prevents deployment errors.

Q: Does the validator check DMARC policy?

A: No, this tool only validates BIMI syntax. BIMI requires DMARC with p=quarantine or p=reject. Use the DMARC Inspector to verify your policy.

Complementary tools

Tool	Purpose
BIMI Inspector	Verify BIMI record published in DNS
BIMI Generator	Generate a valid BIMI record for your domain
DMARC Inspector	Verify DMARC policy (BIMI prerequisite)
SPF Inspector	Validate associated SPF record
DKIM Inspector	Verify DKIM public key
Email Tester	Test complete authentication with a real email

Useful resources

BIMI Group - Official specifications (BIMI consortium)
SVG Tiny PS Profile (W3C)
DigiCert VMC (get a certificate)
Entrust VMC (get a certificate)
Google - BIMI requirements (Gmail guide)

Verify SVG logo and VMC certificate before publication

Instant validation

SVG Tiny-PS logo

VMC certificate inspection

Clear error messages

Specification compliant