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BIMI syntax checker

What a BIMI record contains

Brand Indicators for Message Identification (BIMI) points mailbox providers to an SVG logo and, when required, to a Verified Mark Certificate (VMC). The TXT record lives at default._bimi.<domain> and is made of semicolon-separated key/value pairs.

Example BIMI record

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

Mandatory and optional tags

  • v — the version. BIMI1 is currently the only accepted value.
  • l — HTTPS URL of the Tiny-PS compliant SVG logo to display.
  • a — HTTPS URL of the VMC. Optional, but required by providers that demand a verified mark.
  • Additional non-standard tags must be avoided; the validator flags unknown keys so you can keep the record interoperable.

What this validator checks

  • Basic syntax and presence of the required tags.
  • HTTPS scheme, redirects and content type of the logo URL.
  • Tiny-PS constraints such as viewBox, forbidden attributes and foreign elements.
  • Download status and metadata of the VMC certificate when provided.

Diagnostics returned by the API

  • TXT envelope — missing version, absent l or a tags and non-standard parameters produce explicit errors (BIMI_VERSION_INVALID, BIMI_LOGO_MISSING, BIMI_AUTHORITY_MISSING, BIMI_PARAM_NON_STANDARD).
  • Logo validation — non-HTTPS URLs, redirects, non-SVG responses or raster/data URIs generate BIMI_LOGO_URL_INVALID, BIMI_LOGO_REDIRECT, BIMI_LOGO_NOT_SVG, BIMI_LOGO_DATA_URI. Tiny-PS checks raise BIMI_LOGO_NOT_TINYPS or BIMI_TINYPS_UNVERIFIED.
  • SVG linting — invalid encoding, missing square viewBox, width/height attributes and other structural issues appear as dedicated diagnostics so you can adjust the asset.
  • VMC retrieval — unreachable or non-PEM certificates, untrusted issuers, expiration and logo/domain mismatches surface as BIMI_VMC_URL_INVALID, BIMI_VMC_UNTRUSTED_CA, BIMI_VMC_EXPIRED, BIMI_VMC_LOGO_MISMATCH.

Before you publish

  • Enforce DMARC with a policy of quarantine or reject; BIMI will be ignored otherwise.
  • Host the SVG logo on HTTPS, without authentication and under your control.
  • Keep the SVG minimal: square viewBox, no external references, no scripts and explicit Tiny-PS compliance.
  • Ensure the VMC is up to date and issued for the domains you intend to display.

The validator highlights every warning, error and piece of metadata so you can ship a BIMI record that providers accept without guessing.