It looks like Gmail will have support for BIMI! As announced by Agari, Google will be running a BIMI pilot program soon. Read all about it here.
If you didn't already know, BIMI is meant to be a simple method for a brand or domain owner to publish a logo that is meant to be displayed adjacent to their email messages in an email client or webmail platform. Yahoo has beta-level support for it today.
Google previously would show a logo defined by the Google Plus profile associated with that email address, but future support for that was thrown in doubt when Google announced the shutdown of end user access to the Google Plus platform. Existing logos in place still seem to work. It's unclear what will happen in the future with regard to currently published logos or brand avatars.
Google and Yahoo seem to be the only mail platforms with announced support for BIMI at this time. Still, that's a significant chunk of a marketer's B2C subscriber list, covering Gmail, AOL, Yahoo and Verizon email domains.