BIMI (Brand indicators to message Identification) is an industry-standard in development and is attempting to encourage the adoption of strong email authentication to combat fraud, spoofing, and fake emails by showing authentic brand images within the inbox. Various mailbox providers, including Gmail, AOL, and Fastmail, live with the BIMI standard. Are you interested in improving the security and efficiency of customers of your mailbox service by implementing this latest standard? If you're using Halon MTA, you're ready to begin. Halon MTA's BIMI software handles the bulk of the work by confirming the inbound email indicators and attaching images to emails to display in the user email inbox. At present, there is only a handful of MUAs that have BIMI support. However, should you create your app or webmail, the BIMI group offers instructions on how to show the verified logo on your interface for users.

What BIMI is, and how does it work.

Shortly, BIMI displays verified brand images in the users' inboxes and is visible before emails are opened. It expands on the current standards for authentication of emails (SPF, DKIM, and DMARC). It encourages email providers to adopt the technologies to increase their image as a brand. According to research that only 24 percent of Fortune 500 sending domains are authenticated. BIMI increases visibility and engagement for brands and simultaneously improving security for users. It consists of the following steps:
The company that is sending the email first has to establish an email security system (enforcing DMARC) for their domain name.
The brand then designs an image that is appropriate to its trademarked logo. Additionally, they apply to obtain the Verified Mark Certificate (VMC), place it in an HTTPS server, and link it using a BIMI DNS record.
If a mailbox service that is BIMI-enabled (like Gmail) receives an email from a brand to one specific recipient, its MTA first confirms that the email comes sent by the brand that is sending it via email authentication such as DMARC.
If the email has been authenticated successfully, the mailbox service's MTA examines whether the sending domain's domain is BIMI and, if it does, checks the logo against VMC certification authorities or another reputation system.
When the logo of the business's BIMI logo is verified, it's added to an email (for instance, as a header) before when the email goes out to an email address to the receiver.
Then, the recipient glances at her email inbox by using the mailbox service's webmail application, which displays the company's logo in addition to an address and a subject on the list of emails.

Beginning using BIMI Validation.
Halon has been the first major commercial MTA to support several of the most exciting new security standards, including DMARC, EdDSA DKIM (elliptic curve), DANE, and MTA-STS. As far as we know, we're the only one to have the BIMI validation feature in addition. The BIMI validation program is 182 characters of Halon script, which I consider quite impressive (especially given that it contains the basic ASN.1 parser).
Original source: https://medium.com/@rawatnimisha/adding-bimi-to-your-mailbox-servic...