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BIMI Explained: How Verified Brand Logos Transform Email Authentication
TL;DR
- BIMI (Brand Indicators for Message Identification) is an email specification that allows domain owners to display a verified brand logo next to authenticated messages in supported email clients. It transforms email authentication from a behind-the-scenes technical requirement into a visible trust signal.
- BIMI requires DMARC enforcement–
p=quarantineorp=reject-before any logo can be displayed. This makes BIMI a powerful incentive for organisations to complete their email authentication journey. - Two certificate options exist for 2026: VMCs (Verified Mark Certificates) require a registered trademark, while CMCs (Common Mark Certificates)-introduced in early 2025-do not require a trademark but need proof of public logo usage for at least 12 months.
- BIMI delivers measurable engagement improvements: studies show 23% higher open rates, 31% reduction in spam folder placement, and 18% improvement in click-through rates for BIMI-enabled emails.
- Supported email clients in 2026 include Gmail (full support across web and mobile), Yahoo Mail, AOL, Apple Mail (iOS 16+ and macOS Ventura+), and Fastmail. Gmail and Apple Mail require a VMC or CMC; Yahoo displays BIMI logos without certificate validation.
What Is BIMI?
BIMI stands for Brand Indicators for Message Identification. It is an email specification that permits domain owners to coordinate with Mail User Agents (MUAs)-such as Gmail, Yahoo Mail, and Apple Mail-to display brand‑specific indicators (logos) next to properly authenticated messages.
The BIMI specification is currently an IETF Internet-Draft with an intended status of Standards Track, expected to be published as an RFC in late 2026. The draft is maintained by the AuthIndicators Working Group and is set to expire on 2 November 2026.
There are two aspects of BIMI coordination:
- A scalable mechanism for domain owners to publish their desired indicators
- A mechanism for Mail Transfer Agents (MTAs) to verify the authenticity of the indicator
Domain owners communicate their desired indicators through the BIMI Assertion Record in DNS, and that record is interpreted by MTAs and MUAs.
Why BIMI Matters
BIMI sits at the intersection of email authentication and brand marketing. It provides:
- Visible trust signals: recipients see a verified logo, not just a technical authentication result
- Incentive for DMARC adoption: BIMI requires DMARC enforcement, encouraging organisations to complete their authentication setup
- Consumer confidence: studies show BIMI delivers up to a 90% increase in consumer confidence
- Improved engagement: consistent logo exposure in the inbox lifts open rates, click-through rates, and brand recall
How BIMI Works
BIMI adds a visible trust signal-your verified logo-next to authenticated emails. The process follows these steps:
The Authentication Foundation
BIMI builds directly on existing email authentication protocols:
| Layer | Protocol | BIMI’s Role |
|---|---|---|
| Layer 1 | SPF | Authorises sending IPs |
| Layer 2 | DKIM | Cryptographic signing |
| Layer 3 | DMARC | Policy enforcement |
| Layer 4 | BIMI | Verified logo display |
BIMI is the newest layer, sitting on top of all three authentication protocols. Without DMARC enforcement, BIMI cannot function.
BIMI Requirements
DMARC Enforcement (Mandatory)
DMARC at p=quarantine or p=reject is required before BIMI can display a logo. Mailbox providers first verify DMARC alignment at an enforcement policy before they fetch the BIMI DNS record.
Recommendation: Complete your DMARC implementation before pursuing BIMI. If you are not yet at enforcement, this is the time to finish the journey.
BIMI-Compliant SVG Logo
The logo must be in SVG Tiny 1.2 Portable/Secure (SVG Tiny PS) format.
Critical requirements from the BIMI specification:
| Requirement | Detail |
|---|---|
| SVG version | version="1.2" and baseProfile="tiny-ps" |
| ViewBox | Square aspect ratio (equal width and height) |
| Minimum size | 96 × 96 pixels or larger |
| File size | Recommended under 32 KB |
| No embedded rasters | No <image> elements or base64-encoded raster data |
| No JavaScript | No script elements or event handlers |
| No foreignObject | <foreignObject> is not permitted |
| No external references | Fully self-contained; no external files via xlink:href, href, or url() |
| Solid colour background | Logo should appear on a solid colour background |
| Title element | Recommended for accessibility compliance |
Important: Web SVGs often fail BIMI validation because they use features valid in browsers but forbidden in BIMI – embedded images, JavaScript, CSS animations, external fonts, or filter effects.
Mark Certificate (VMC or CMC)
Two certificate options exist in 2026:
| Certificate | Trademark Required | Validation | Supported By |
|---|---|---|---|
| VMC (Verified Mark Certificate) | yes – registered trademark with WIPO-recognised office | Logo must be legally trademarked | Gmail, Yahoo, Apple Mail |
| CMC (Common Mark Certificate) | no | Proof of public logo usage on domain for ≥12 months | Gmail (introduced early 2025) |
VMC requirements:
- Active trademark registration with a WIPO-recognised intellectual property office
- Logo prepared to the SVG Tiny Portable/Secure specification
- BIMI DNS record configured alongside DMARC enforcement
CMC requirements:
- No registered trademark required
- Proof that your logo has been publicly displayed on your domain for at least 12 months
- Same SVG logo requirements as VMC
Note: Yahoo Mail displays BIMI logos without VMC validation, while Gmail and Apple Mail require a valid VMC or CMC.
BIMI DNS Record
The BIMI record is a DNS TXT record published at default._bimi.yourdomain.com.
Basic BIMI record (logo only):
v=BIMI1; l=https://www.example.com/logo.svgBIMI record with certificate (required for Gmail):
v=BIMI1; l=https://www.example.com/logo.svg; a=https://www.example.com/vmc/logo.pemBIMI record with AVP tag (introduced in 2025):
v=BIMI1; l=https://www.example.com/logo.svg; a=https://www.example.com/vmc/logo.pem; avp=preferThe avp (Avatar Preference) tag sets the display preference with two values:
prefer– prioritises the BIMI logo over other avatar sourcesonly– only displays the BIMI logo, no fallback
Available BIMI tags:
| Tag | Definition |
|---|---|
v | Version (BIMI1) |
l | Location of the logo (SVG file URL) |
a | Evidence-URL of the Mark Certificate (PEM file) |
avp | Avatar Preference-display preference for the indicator |
DNS record example:
Host: default._bimi.example.com
Type: TXT
TTL: 3600 (1 hour)
Value: v=BIMI1; l=https://images.example.com/brand/logo.svg; a=https://images.example.com/brand/certificate.pemImplementation note: It can take up to 48 hours for BIMI to start working after publishing the DNS record.
Supported Email Clients (2026)
Full BIMI Support
| Email Client | VMC/CMC Required | Notes |
|---|---|---|
| Gmail | yes (VMC or CMC) | Full support across web and mobile |
| Apple Mail | yes (VMC or CMC) | iOS 16+, iPadOS 16+, macOS Ventura+ |
| Yahoo Mail | no | One of the earliest adopters |
| AOL | no | Consistent BIMI support |
| Fastmail | yes | Full support |
| Cloudmark | – | Supports BIMI |
Considering or Limited Support
| Email Client | Status |
|---|---|
| Microsoft Outlook | No BIMI support as of May 2026 |
| Microsoft 365 | No BIMI support as of May 2026 |
| Seznam.cz | Considering |
| Zoho Mail | Considering |
Source: BIMI Group, May 2026
Adoption forecast: Industry analysts project that over 70% of business email traffic will flow through BIMI-enabled platforms by late 2026. Expected provider support is 85% by the end of 2026.
Benefits of BIMI
Measurable Engagement Improvements
According to comprehensive technical studies, BIMI-enabled emails deliver:
| Metric | Improvement |
|---|---|
| Open rates | 23% higher (consumer email providers) |
| Spam folder placement | 31% reduction |
| Click-through rates | 18% improvement |
| Consumer confidence | Up to 90% increase |
| Brand recall | 44% boost |
Provider-specific performance:
- Gmail (consumer): 28.7% open rate (22.3% baseline)-28.7% increase
- Google Workspace: 38.9% open rate (31.2% baseline)-24.7% increase
- Yahoo/AOL: 19.2% average open rate improvement, 26% decrease in delete-without-opening
Industry-specific results:
- Fashion/Apparel: 32% average open rate lift, 41% improvement in mobile opens
- Consumer Electronics: 28% open rate improvement, 45% reduced spam complaints
- Financial Services: 26% open rate increases, 22% CTR improvements, 67% reduction in phishing reports
- B2B Software: 18% open rate improvements, 15% better engagement in automated sequences
Brand Protection and Trust
BIMI provides immediate protection against brand spoofing and phishing. When recipients see a verified brand logo alongside an email, they can immediately trust that it is an actual email from you and not a dangerous phishing attempt.
For financial institutions, the 67% reduction in phishing reports is particularly significant-legitimate financial communications are often mistaken for phishing attempts.
Visible DMARC Reward
BIMI transforms DMARC enforcement from a technical compliance requirement into a visible marketing benefit. Organisations that invest in email authentication gain a competitive advantage through improved brand visibility and engagement.
Future-Proof Authentication
As BIMI adoption grows, organisations that implement it early gain a first-mover advantage in brand recognition and trust. Expected provider support of 85% by late 2026 means BIMI will soon be table stakes for serious email senders.
Implementation Checklist
Phase 1: Authentication Foundation
- Configure SPF for all sending sources
- Implement DKIM signing with 2048-bit keys
- Deploy DMARC at
p=quarantineorp=reject
Phase 2: Logo Preparation
- Create SVG logo in SVG Tiny 1.2 Portable/Secure format
- Verify
version="1.2"andbaseProfile="tiny-ps" - Ensure square viewBox (equal width and height)
- Confirm minimum size of 96 × 96 pixels
- Keep file size under 32 KB
- Remove all script elements, external references, and embedded rasters
- Validate with a BIMI logo validator before publishing
Phase 3: Certificate (if required)
- For VMC: obtain registered trademark with WIPO-recognised office
- For CMC: confirm 12+ months of public logo usage on domain
- Apply for VMC or CMC through a Certificate Authority
Phase 4: DNS Publication
- Publish BIMI TXT record at
default._bimi.yourdomain.com - Include
v=BIMI1andl=(logo URL) - Include
a=(certificate URL) for Gmail and Apple Mail - Set TTL to 3600 seconds (1 hour)
- Wait up to 48 hours for propagation
Phase 5: Testing and Monitoring
- Test with BIMI-ready email clients (Gmail, Yahoo, Apple Mail)
- Monitor DMARC reports for authentication alignment
- Verify logo display in supported inboxes
- Check certificate validation status
Common BIMI Mistakes
| Mistake | Why It’s a Problem | Fix |
|---|---|---|
| DMARC not at enforcement | BIMI requires p=quarantine or p=reject | Complete DMARC implementation first |
| Invalid SVG format | Web SVG features are forbidden in BIMI | Use SVG Tiny PS; validate before publishing |
Missing baseProfile | File is not recognised as BIMI-compliant | Add baseProfile="tiny-ps" to SVG root |
| External references in SVG | BIMI requires self-contained files | Remove all xlink:href and external url() references |
| Embedded raster images | <image> elements are forbidden | Use pure vector graphics only |
| File size too large | May cause display issues | Keep under 32 KB |
| Incorrect DNS record format | Record is ignored or misinterpreted | Use correct syntax: v=BIMI1; l=URL; a=URL |
| Missing certificate for Gmail | Gmail requires VMC or CMC | Add a= tag pointing to PEM certificate |
| Not waiting for propagation | DNS changes take time | Allow up to 48 hours |
Key Takeaways
- BIMI displays verified brand logos in supported email clients, transforming email authentication from a behind-the-scenes technical requirement into a visible trust signal.
- DMARC enforcement (
p=quarantineorp=reject) is mandatory for BIMI display. This makes BIMI a powerful incentive to complete your authentication journey. - Two certificate options exist for 2026: VMCs require a registered trademark; CMCs do not require a trademark but need 12+ months of public logo usage.
- BIMI delivers measurable results: 23% higher open rates, 31% reduction in spam placement, and 18% improvement in click-through rates.
- Supported in 2026 by Gmail, Yahoo Mail, AOL, Apple Mail, and Fastmail. Gmail and Apple Mail require a VMC or CMC.
- Implementation requires DMARC enforcement, a BIMI-compliant SVG logo, a Mark Certificate (VMC or CMC), and a DNS TXT record.
- The BIMI specification is an IETF Internet-Draft with intended Standards Track status, expected to be published as an RFC in late 2026.
- Expected provider support of 85% by the end of 2026 means BIMI will soon be essential for serious email senders.
Conclusion
BIMI (Brand Indicators for Message Identification) represents a significant evolution in email authentication. By allowing domain owners to display verified brand logos in supported inboxes, BIMI transforms email authentication from a technical requirement into a visible trust signal that consumers immediately recognise.
The value proposition is clear: 23% higher open rates, 31% reduction in spam placement, up to 90% increase in consumer confidence-all from implementing a system that also protects your brand from impersonation and phishing attacks.
Implementation requires DMARC enforcement, a BIMI-compliant SVG logo, a Mark Certificate (VMC or CMC), and a DNS TXT record. The process is not trivial, but the return on investment is substantial. With expected provider support of 85% by the end of 2026, BIMI is becoming table stakes for serious email senders.
For organisations that have already implemented DMARC, BIMI is the logical next step-turning a compliance project into a competitive advantage.
Need help implementing BIMI for your domain? Playful Sparkle has been engineering digital products since 2004, offering Web Development, security consulting, and technical implementation services. Our team can help you configure DMARC enforcement, prepare BIMI-compliant SVG logos, obtain Mark Certificates, and publish BIMI DNS records. Contact us to discuss how we can help you display your verified brand logo in the inbox.
Zsolt Oroszlány
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