How BIMI works
A domain publishes a BIMI DNS TXT record pointing to a hosted SVG logo file (and optionally a Verified Mark Certificate). When a message arrives that passes DMARC with sufficient enforcement, the receiving mailbox provider checks for a BIMI record and, if present and valid, displays the brand’s logo next to the message in the inbox — functioning as a recognizable, hard-to-spoof trust signal for recipients.
Why BIMI’s prerequisite matters more than BIMI itself
The real value of pursuing BIMI often isn’t the logo — it’s that getting there forces a domain to have fully enforced SPF, DKIM, and DMARC (at quarantine or reject, not none) first. Many domains that go through the BIMI setup process see authentication and deliverability improvements from that prerequisite work alone, independent of whether the logo ends up displaying everywhere.
Verified Mark Certificates (VMCs)
A VMC is a certificate issued by an authorized certificate authority that cryptographically ties a BIMI logo to a registered trademark, adding a layer of identity verification beyond DMARC alone. Some mailbox providers display BIMI logos without one; others require it. This makes BIMI adoption meaningfully more involved (and costlier) than SPF/DKIM/DMARC alone, which is why adoption has been slower despite the deliverability-adjacent benefits of the prerequisite authentication work.
BIMI doesn’t improve deliverability directly
BIMI is a display/branding feature, not a spam-filtering input — a message isn’t more or less likely to land in the inbox because of a BIMI logo. Its indirect benefit comes entirely from requiring strong DMARC enforcement as a prerequisite, and from the trust/recognition effect a verified logo has on a recipient once the message is already in front of them.