Will BIMI become a standard trust indicator for email like SSL/TLS for websites?

Key findings

• Enhanced Trust: BIMI aims to provide a visual cue of sender authenticity, potentially making it harder for bad actors to use lookalike domains for phishing. The requirement for a trademark and a VMC adds a layer of identity verification beyond standard email authentication.
• Identity Verification: Unlike generic SSL/TLS certificates, which primarily secure communication, BIMI with a VMC verifies the identity of the sender's brand. This means the logo displayed is officially tied to a legally trademarked entity.
• DMARC Requirement: A foundational element of BIMI is the strict requirement for a DMARC policy at enforcement (p=quarantine or p=reject), which significantly improves email security by preventing unauthorized use of a domain. Learn more about BIMI implementation requirements.
• Phishing Deterrent: Proponents argue that BIMI could be a powerful tool against phishing, as it would be exceptionally difficult for scammers to obtain a VMC for a fraudulent logo that mimics a legitimate brand.

Key considerations

• Comparison to EV TLS: BIMI's reliance on VMCs is often compared to Extended Validation (EV) TLS certificates for websites, which offered a green padlock for higher trust. However, EV TLS did not achieve widespread user recognition or a significant trust impact, leading to its decline in visibility. This suggests that the visual display alone may not guarantee user trust.
• Cost and Complexity: Obtaining a trademark and a VMC involves significant costs (e.g., $400 for trademark, $1000 for VMC annually) and a labor-intensive identity verification process. This financial and administrative barrier could limit BIMI's adoption, especially among small to medium-sized businesses, potentially creating an email caste system.
• Mailbox Provider Control: Mailbox providers ultimately control whether a BIMI logo is displayed, even with a valid VMC, based on sender reputation. This means a VMC isn't a guaranteed display, and some providers may opt for self-asserted BIMI based on DMARC and domain reputation, which lessens the trust value tied to VMCs. The BIMI Group provides further documentation on VMC requirements.
• Barriers to Entry for CAs: Establishing new Certificate Authorities (CAs) for BIMI is challenging. It requires convincing major mailbox providers to trust their vetting processes, ensure sufficient policing of customers, and maintain a robust revenue stream to support these efforts. This is a significant hurdle that limits competition and potentially keeps costs high.

Key opinions

• Brand Visibility: Many marketers believe BIMI's primary benefit is increasing brand visibility in the inbox, making emails more recognizable and potentially improving open rates. This is highlighted by the focus on displaying logos next to authenticated emails.
• Increased Trust (Long-term): There's an optimistic view that BIMI will eventually build trust among recipients, who will learn to associate the verified logo with legitimate communications, especially if it becomes a widespread standard.
• Anti-Phishing Potential: Some marketers see BIMI as a crucial step in combating phishing, as the stringent requirements for obtaining a VMC make it difficult for bad actors to impersonate established brands effectively. This directly relates to BIMI's impact on email engagement.
• DMARC Adoption Driver: Marketers anticipate that the desire for BIMI will accelerate DMARC adoption, as DMARC enforcement is a prerequisite. This encourages better email authentication practices across the board.

Key considerations

• High Barrier to Entry: The costs and administrative burden of obtaining a trademark and a VMC are significant, posing a challenge for smaller businesses. This means BIMI implementation costs remain a concern.
• Potential for Disadvantage: If BIMI becomes a strong trust signal, companies unable to implement it due to cost or complexity might find their emails perceived as less trustworthy, potentially creating a tiered email ecosystem.
• Lack of Ubiquity (Currently): Marketers recognize that widespread adoption will take time, as not all email clients fully support BIMI, and not all senders have implemented the necessary prerequisites. This means the visual trust signal is not yet universally present.
• Primary Benefit as Branding: While trust is a goal, many marketers initially adopt BIMI more for its branding benefits, viewing the logo display as a way to stand out rather than a strict security measure in the same vein as DMARC.

Key opinions

• Not a Pure Trust Indicator: Experts argue that BIMI, in itself, is not a trust indicator beyond what SPF, DKIM, and DMARC already provide. It primarily adds an image (logo) as a marketing and branding element.
• VMC as Authentication Layer: The Verified Mark Certificate (VMC) component of BIMI adds a Certificate Authority (CA) into the process to validate the sender's identity, making it harder for bad actors to spoof logos. This is where BIMI adds a unique layer to email authentication, particularly for DMARC enforcement at the organizational level (p=reject) as discussed in BIMI's DMARC requirements.
• Cost is a Feature: The cost of VMCs and the intensive identity verification process are not accidental; they are designed to be a barrier to entry for malicious actors, effectively making the cost a feature of its security model.
• Parallel to EV TLS Certificates: BIMI's validation process is often compared to Extended Validation (EV) TLS certificates. Experts suggest EV TLS didn't become ubiquitous because it offered little practical reassurance over Domain Validated (DV) certificates for most users, indicating a potential similar trajectory for BIMI if it's seen as primarily for website SSL/TLS and less for core trust.

Key considerations

• Centralized Trust Challenge: Unlike website SSL/TLS, where a few browser companies drive CA trust, new BIMI CAs must convince numerous mailbox providers individually, making it politically and financially difficult to scale and centralize trust.
• Mailbox Provider Discretion: Even with a VMC, mailbox providers retain the right to display or suppress the logo based on their internal reputation systems. This means a VMC does not guarantee logo display, reducing its guaranteed trust value.
• Trademark vs. Real-world Threat: While trademarks offer legal protection, they are a post-hoc enforcement mechanism. For phishing, pre-emptive identity verification by CAs is crucial, requiring a labor-intensive process that goes beyond merely holding a trademark.
• Existing Reputation Infrastructure: The current email ecosystem already has robust reputation infrastructure (e.g., DMARC, blacklists/blocklists, spam filters) for identifying bad actors. It is not yet clear if BIMI provides a sufficiently incremental security benefit to warrant its widespread mandatory adoption as a trust indicator.

Key findings

• Core Function: BIMI is officially described as enhancing brand value by connecting verified logo displays to the increased protection provided by DMARC enforcement. It adds brand identification to improved authentication against domain impersonation.
• Strong Authentication Requirement: A key requirement for BIMI is a DMARC policy set at an enforcing level (p=quarantine or p=reject). This provides brands with the opportunity to prevent domain abuse and potentially improve customer trust.
• Verified Mark Certificates (VMCs): VMCs are central to BIMI's ability to display a verified logo. They serve as cryptographic proof that the organization has the right to use the specified logo for email. This is an important step for ensuring BIMI SVG and certificate validation.
• Anti-Impersonation: BIMI builds on the foundation of DMARC-based trust and authentication to make it significantly harder for unauthorized parties to impersonate a brand through email, thereby reducing phishing risks.

Key considerations

• Mailbox Provider Support: While the standard exists, its effectiveness depends on widespread support from email clients and mailbox providers. Some providers may display BIMI logos without requiring a VMC, relying solely on DMARC and reputation, which affects its universal trust value. Review BIMI availability for email clients.
• Reputation Integration: Even with a VMC, the display of a logo is not guaranteed; it is often still contingent on the sender's overall email reputation. This implies that BIMI is part of a larger, more complex trust calculation by mail systems.
• Trademark Requirement: The requirement for a globally registered trademark for the logo is a fundamental aspect of VMC issuance. This ensures a legal basis for the brand identity displayed, but adds a significant prerequisite.
• Long-term Evolution: The BIMI ecosystem is still evolving, with discussions ongoing regarding the possibility of reducing barriers to entry for CAs and making VMCs more accessible, which could impact its trajectory as a standard trust indicator.