BIMI (Brand Indicators for Message Identification) lets a domain associate a brand logo with its outbound mail. Supporting clients (Gmail, Apple Mail, Yahoo) display the logo next to the sender's name in the inbox, raising recipient trust and brand recognition for legitimate mail.
The TXT record lives at default._bimi.<domain> and carries two key tags: l= points to the logo SVG (must be the special "SVG Tiny PS" profile -- a stripped-down SVG variant browsers and mail clients can render safely), and a= optionally points to a Verified Mark Certificate (VMC) that some clients require before honoring the logo.
Critical prerequisite: BIMI is only honored when DMARC is enforced (p=quarantine or p=reject). A BIMI record with p=none (or no DMARC at all) is ignored by every major receiver -- a common silent misconfiguration where the domain operator publishes the BIMI record without realizing the logo will never appear.
VMC requirements vary: Gmail requires it as of 2024 for most senders; Apple Mail and Yahoo accept BIMI without VMC for many domains. VMCs are issued by certificate authorities like DigiCert and Entrust and require trademark registration for the logo.