DELIVTERMS: Common Mark Certificate (CMC)

It is time to decode another deliverability acronym here on Spam Resource! Today, we're going to talk about CMC, which stands for "Common Mark Certificate."

A CMC is something that a domain owner will purchase to go along with their BIMI ("Brand Indicators for Message Identification") sender logo implementation. BIMI is the specification to allow a domain owner to publish details of a logo meant to show up in the inbox next to email sends from that domain.

There are two types of certificates for BIMI logos in 2024, VMC (Verified Mark Certificate) or CMC (Common Mark Certificate). Things to note:

Various mailbox providers require a VMC or CMC certificate in order to display your desired BIMI logo.

Currently, Gmail is the only mailbox provider supporting CMC. Gmail also supports VMC.
Various other mailbox providers require VMC, including Apple.
Yahoo does not require any certificate today.

VMC and CMC certificates are purchased from Certificate Authorities (CAs). The two CAs that sell VMC and CMC certificates today are Digicert and Entrust. The purchase process involves vetting to ensure that your company exists and is verifiable via various means.

As part of the purchase process, the Certificate Authority will also vet the desired logo:

For VMC, the logo must be trademarked in a supported jurisdiction. The desired BIMI log must match the trademarked logo.
For CMC, the logo does not need to be trademarked, but must be demonstrably visible on an "Internet Archive" version of the company's website at least twelve months prior. CMC also supports logos that are modified variations of a trademarked logo.

Here's how CMC versus VMC determines where your logo will display:

A sender who implements BIMI with no CMC or VMC will have the logo show only at Yahoo Mail (if it meets their volume and reputation requirements) and various other smaller mailbox providers. The logo will not show on Apple webmail and Apple applications, nor will it show on Gmail.
A sender who implements CMC will see their logo displayed on Yahoo Mail and Gmail.
A sender who implements VMC will see their logo displayed on Apple, Yahoo Mail, and Gmail.

Google announced CMC support for BIMI logos on Gmail in late September, 2024:

Find the announcement from Google here: https://xnnd.com/7p7c
Find Valimail's coverage of the announcement here: https://xnnd.com/ka67
I blogged about that announcement here on Spam Resource: https://xnnd.com/1sfu
And here is information on this announcement from the Authindicators Working Group, the folks behind the BIMI standard:https://xnnd.com/6gak

Note that Google will display a blue checkmark to indicate that a sender has properly implemented BIMI, if the BIMI logo configuration includes a VMC. If the logo configuration only includes CMC, the blue checkmark will not be displayed.

Learn more:

Google has a support page where they explain VMC.
BIMI has its own DELIVTERMS page here on Spam Resource.
My BIMI FAQ (from May 2023) covers more Q&A related to BIMI and VMC.

And of course, don't forget to check out the DELIVTERMS section here on Spam Resource, where we define the common terms used in email technology and deliverability.