What is the correct syntax for a Brand Indicators for Message Identification (BIMI) record in the Domain Name System (DNS)?

BIMI records are stored in the DNS as a TXT (text) record with the following syntax. For details on all BIMI technical specifications, please visit:

• bimigroup.org
• BIMI Specifiations

Please note that all of the examples below are for illustrative purposes only. Be sure to use your own selector, domain and logo information or your logo will not display.

Components of a BIMI DNS record

All of the components listed below are required in order for BIMI to work correctly.

• Selector: Allows the domain owner to use different logos for different subscribers, similar to a DKIM selector.
  • The value is specified by the sender in the BIMI-Selector header.
  • The default value is "default". The "default" selector is used to look up the BIMI record when a BIMI-Selector header is not inserted into an email.
  • A mailbox provider looks at the selector name in your email to determine where to look up the BIMI record for your domain.
• BIMI subdomain: The subdomain that identifies the record as a BIMI record.
  • The value is always "_bimi".
• Domain name:  The domain name where the BIMI record is stored in the DNS.
• Top level domain name:  The top level domain associated with your domain name (typically .com, .net, .org, etc)
• Assertion record: Stores your logo information.

Correct syntax for the DNS record

<selector>.<bimisubdomain>.<domainname>.<topleveldomainname>

 Examples:

• brandx._bimi.brand.com
• default._bimi.zzzcompany.net

Components of the Assertion record

• v = Version: the value is always BIMI1. (Required)
• l = Logo location: the URL of your logo using HTTPS only. (Required)
• a = Authority evidence location: the URL of your BIMI evidence document, such as a Verified Mark Certificate (VMC), used to validate domain ownership. (Optional; left blank if you don't have an evidence document)

Correct syntax for the Assertion record

v=<version>; l=<location URL>; a=<URL>;

Example:

• v=BIMI1; l=https://subdomain.sampledomain.com/image/logo.svg; a=https://subdomain.brand.com/vmc/logo.pem;

Example of a full BIMI TXT record as seen in the DNS for a domain

• No evidence document (such as a VMC):
  • brandx._bimi.brand.com IN TXT "v=BIMI1; l=https://subdomain.brand.com/image/logo.svg; a=;"
• With an evidence document:
  • default._bimi.brand.com IN TXT "v=BIMI1; l=https://subdomain.brand.com/image/logo.svg; a=https://subdomain.brand.com/vmc/logo.pem;"