Glossary · Authentication
A VMC or CMC is a certificate that ties a logo to a domain, required by Gmail and Apple Mail before they display a BIMI logo.
Mark certificates are X.509 certificates from a small set of approved certificate authorities. They embed the logo itself and name the domains it may appear for. The BIMI record points to the certificate with its a= tag.
A Verified Mark Certificate (VMC) requires the logo to be a registered trademark. A Common Mark Certificate (CMC) is the newer option for logos that aren't trademarked, backed by evidence that the logo has been in use. Both are paid annually and involve identity verification of the organisation.
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