There are only a few tags available for your domain's BIMI assertion record. The assertion record is part of the DNS TXT record for your domain. Using tags in your BIMI assertion record that are not listed here will be ignored by a participating mailbox provider.
- v: This tag identifies the record as a BIMI record.
- The value of this tag must be BIMI1 and be the first tag on the list.
- The assertion record will be ignored if the value of this tag is empty or if it does not match BIMI1 exactly.
- l: This tag (a lower case L) identifies the location of the logo you wish to be displayed.
- The location of the logo is represented by a URL with 'HTTPS' only - it will not work with 'HTTP'.
- The image format for the logo must be SVG (.svg) or your logo will not display correctly. More image formats may be accepted in the future.
- The image must be a square, centered, and only be your logo without text.
- The assertion record will be ignored if the value of this tag is empty.
This tag is not required, however, as more mailbox providers adopt BIMI for their users, it may become required at specific mailbox providers in order for your logo to appear.
- a: This tag is used to validate domain ownership using a trust certificate. The accepted values are:
- self: no validation option, similar to not having an 'a' tag.
- cert: provides an HTTPS URL to a Verified Mark Certificate (aka Mark Verified Certificate) that can be used to validate the logo in the l tag.
- mva: specifies an HTTPS URL to an API endpoint that can be queried for validation.