BIMI (Brand Indicators for Message Identification).

BIMI is a specification that allows email senders to display their brand logo as the avatar in supported inboxes (Gmail, Apple Mail, Yahoo) instead of the generic letter icon. Setting up BIMI requires DMARC enforcement (p=quarantine or p=reject), an SVG logo hosted at a known location, and — for Gmail — a Verified Mark Certificate (VMC) from a certified issuer.

BIMI is one of the highest-trust signals available in email today. Senders with BIMI typically see lift in open rates because recipients recognise the brand logo before opening the message.