BIMI stands for "Brand Indicator For Message Identification".
Its most obvious use is to put your logo/icon next to your emails in contacts' inboxes.
Requirements:
DMARC policy of quarantine or above.
Logo in a SVG file type (An SVG file type is a vector-based image. This means any attempt to make the image smaller or larger will not affect the final quality)
a valid VMC (Verified Mark Certificate) issued by an MVA (Mark Verifying Authority)
Once you have created a domain and provided a URL to your hosted logo and VMC, we will generate this record and go through the process with you.
A typical BIMI record looks like this:
default._bimi.[top domain] IN TXT v=BIMI1; l=[SVG URL]; a=[PEM URL]"
eg: sender's home domain is example.com, they send from email.example.com and they do not have a certificate:
default._bimi.example.com. 299 IN TXT "v=BIMI1; l=https://logos.example.com/_email/logos/bimi-icon.svg"
As you see the sending sub-domain is irrelevant in the BIMI record.
The sub-domain comes into it where the dmarc record in the sending (sub)domain must have p=reject or p=quarantine, when it often starts out as p=none.