The one-sentence version#
A CMC is a lower-tier BIMI certificate introduced in 2024 for brands without a registered trademark. Eligibility requires 12 months of prior logo use or a government-issued mark. Gmail displays the logo but not the blue checkmark.
Why you should care#
It opens BIMI in Gmail to small businesses and new brands that cannot afford or have not completed trademark registration.
The mental model#
Think of Common Mark Certificates (CMC) as a contract between you and the mailbox providers receiving your mail. You publish or configure something they can check; they check it on every message; the result feeds their decision about where your message lands. Everything below is about making that check pass consistently.
Your first setup, step by step#
- Document at least 12 months of logo use (Wayback Machine snapshots, marketing materials).
- Prepare the logo as SVG Tiny PS.
- Complete organization validation with DigiCert or Entrust.
- Publish the certificate URL in the a= tag of your BIMI record.
Words you will see#
- Mailbox provider: Gmail, Microsoft, Yahoo, Apple, and the corporate gateways that decide where mail lands.
- Authentication: proof that a message is from who it says it is (SPF, DKIM, DMARC).
- Reputation: the provider's running score of your domain and IP.
- Placement: whether a message reaches the inbox, spam, or is rejected.
Common mistakes#
- Expecting the blue checkmark; CMC does not qualify.
- Changing the logo after issuance, which invalidates the certificate.
Frequently asked questions#
Which providers accept CMC?
Gmail accepts CMC as of 2024. Apple accepts VMC and CMC. Yahoo does not require a certificate.
Can I upgrade from CMC to VMC?
Yes, once the trademark registers. Reissue the certificate and update the a= tag.