What Common Mark Certificates (CMC) is#
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 it matters#
It opens BIMI in Gmail to small businesses and new brands that cannot afford or have not completed trademark registration.
How mailbox providers use it#
Gmail, Microsoft, and Yahoo combine authentication results, sender reputation, and recipient engagement into a placement decision made per message. Common Mark Certificates (CMC) feeds directly into that model, and weaknesses compound with other signals.
How to measure the impact#
- Baseline inbox placement with seed tests before any change.
- Make one change at a time and hold volume steady.
- Re-test after 48 to 72 hours; provider models need time to update.
- Track Postmaster Tools and SNDS alongside your seed results.
Improving it#
- 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.
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.