The plain-English glossary

BIMI glossary.
Every acronym explained.

A quick reference for the words you’ll meet on your BIMI journey.

28 terms, explained simply

Alignment

The relationship between an authenticated SPF or DKIM domain and the visible From domain. A passing result must align to count towards DMARC.

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Authentication

Technical checks that establish whether a message is authorised by a domain or carries a valid domain signature. It does not prove that every claim inside the message is true.

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BIMI

Brand Indicators for Message Identification: a way to publish a brand logo for consideration by supporting inbox providers.

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BIMI selector

The name used to locate a BIMI DNS record. Most deployments begin with default. It is separate from a DKIM selector.

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Certificate authority (CA)

An organisation that issues digital certificates after performing the relevant validation. Mark certificates and web-server TLS certificates serve different purposes.

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CMC

Common Mark Certificate. A mark certificate that can support eligible prior-use or modified registered marks, subject to issuer validation.

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DKIM

DomainKeys Identified Mail. A domain-based digital signature that a receiving server can verify with a published public key.

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DMARC

Domain-based Message Authentication, Reporting, and Conformance. Connects authentication to the visible From domain and publishes policy and reporting preferences.

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DNS

Domain Name System. The distributed directory that publishes domain information, including email authentication and BIMI TXT records.

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Enforcement

For BIMI deployment guidance, a DMARC policy requesting quarantine or rejection with full policy application, rather than monitoring alone.

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Envelope sender

The address supplied during SMTP delivery, commonly reflected in Return-Path. Its domain is used in SPF evaluation and can differ from the visible From address.

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ESP

Email service provider. A service that sends or manages email for an organisation. Using an ESP does not automatically align mail with your domain.

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From domain

The domain in the sender address a person sees in an email. DMARC alignment is evaluated against this identity.

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HTTPS

HTTP over a protected TLS connection. BIMI assets need public HTTPS hosting that a receiving provider can access.

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Mailbox provider

The service receiving and managing a recipient’s mail. It applies its own authentication, filtering, and logo-display rules.

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Mark

The brand symbol or artwork for which an organisation establishes rights. Eligibility depends on the certificate type and issuer requirements.

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MVA

Mark Verifying Authority. An issuer that validates mark-related evidence for BIMI certificates.

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Organisational domain

The registrable domain associated with an organisation, such as example.com. It is not always simply the last two labels of a hostname.

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PEM

A text encoding used to distribute certificate material. In BIMI, the public PEM asset contains the issued certificate and any required chain.

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Quarantine

A DMARC policy requesting that failing messages be treated as suspicious, for example by placing them in spam. Receivers apply local policy.

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Reject

A DMARC policy requesting rejection of failing messages. Test legitimate sending sources before adopting enforcement.

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Self-asserted BIMI

A BIMI assertion without a mark certificate. Accepted by some providers, but insufficient for Gmail BIMI.

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SPF

Sender Policy Framework. Publishes which sending servers are authorised for an envelope domain.

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SVG Tiny PS

Scalable Vector Graphics Tiny Portable/Secure. The restricted vector-image profile used for BIMI logos.

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TLS

Transport Layer Security. Protects network connections, including the HTTPS connection used to fetch BIMI assets.

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TTL

Time to live. A DNS value that affects how long a resolver can cache an answer. It is separate from a mailbox provider’s logo cache.

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TXT record

A type of DNS record containing text. BIMI uses it to publish its version and asset locations.

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VMC

Verified Mark Certificate. A mark certificate for eligible registered or government marks; associated with Gmail’s verification checkmark.

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