What Recipients See
Without BIMI, your emails appear with a generic icon or the first letter of your sender name. With BIMI, your verified brand logo displays as an avatar next to every message in supported clients like Gmail and Yahoo Mail. This visual distinction helps your transactional emails (order confirmations, password resets, shipping notifications) stand out from spam and phishing attempts that may impersonate your domain.Benefits
- Brand Recognition — Your logo appears prominently in the inbox alongside every email sent through Lettr
- Increased Trust — Recipients can visually confirm emails are legitimately from you
- Higher Engagement — Branded emails see measurably higher open rates
- Spam Differentiation — Legitimate emails stand out from phishing attempts impersonating your domain
Requirements
BIMI requires several components to be in place:DMARC Enforcement
Your domain must have DMARC with enforcement enabled:See DMARC Configuration for setup instructions.
- Policy must be
p=quarantineorp=reject - Percentage must be
pct=100
Verified Mark Certificate (VMC)
A certificate from an authorized provider proving logo ownership. Required for Gmail, Yahoo, and other major clients.
How BIMI Works
Email is sent and authenticated
Your email is sent from your domain and arrives at the recipient’s mail server. The server performs SPF, DKIM, and DMARC authentication checks. DMARC must pass with a policy of
quarantine or reject.BIMI DNS lookup
After DMARC passes, the receiving server queries your domain’s DNS for a BIMI TXT record at
default._bimi.yourdomain.com. This record contains the URL to your logo and optionally a VMC certificate.Logo and VMC retrieval
The server fetches your SVG logo from the HTTPS URL specified in the BIMI record. If the mailbox provider requires a Verified Mark Certificate (VMC), it also retrieves and validates the certificate to confirm logo ownership.
Logo Requirements
Your BIMI logo must meet these specifications:| Requirement | Specification |
|---|---|
| Format | SVG Tiny 1.2 Portable/Secure |
| Shape | Square (1:1 aspect ratio) |
| Background | Solid color (no transparency) |
| Minimum size | 32x32 pixels |
| File size | Under 32 KB |
| Hosting | HTTPS URL accessible publicly |
SVG Tiny PS Specifics
BIMI uses a special SVG profile called “SVG Tiny Portable/Secure”:- No external references or links
- No scripts or animations
- Limited element set (basic shapes, paths, text)
- Must include
baseProfile="tiny-ps"andversion="1.2"
Creating a BIMI Record
Add a TXT record to your domain:| Field | Value |
|---|---|
| Type | TXT |
| Name | default._bimi |
| Value | v=BIMI1; l=https://example.com/logo.svg; a=https://example.com/vmc.pem |
Record Parameters
| Parameter | Required | Description |
|---|---|---|
v=BIMI1 | Yes | BIMI version identifier |
l= | Yes | URL to your SVG logo (HTTPS required) |
a= | No* | URL to your VMC certificate |
Without VMC
If you don’t have a VMC yet, you can still set up BIMI for clients that don’t require it:With VMC
For full support including Gmail:Verified Mark Certificates (VMC)
A VMC proves you own the trademark for the logo you’re displaying. It’s issued by authorized certificate authorities.VMC Providers
| Provider | Website |
|---|---|
| DigiCert | digicert.com |
| Entrust | entrust.com |
VMC Requirements
To obtain a VMC, you need:- Trademark Registration - Logo must be registered with a recognized trademark office
- Domain Ownership - Prove you control the domain
- Organization Verification - Business identity verification
VMC certificates cost several thousand dollars annually and require trademark registration. Consider this investment carefully for brand protection benefits.
VMC File Format
The VMC is provided as a PEM file. Host it at an HTTPS URL:VMC Lifecycle
VMC certificates are typically valid for one year. Plan for renewal:- Track expiration — Set a calendar reminder at least 30 days before your VMC expires. If your VMC lapses, Gmail and Yahoo will stop displaying your logo immediately.
- Renew early — Certificate authorities can take several business days to reissue. Start the renewal process at least 2 weeks before expiration.
- Update the hosted file — After renewal, replace the PEM file at your hosted URL. The BIMI DNS record doesn’t need to change as long as the URL remains the same.
- Verify after renewal — Send test emails to Gmail and Yahoo to confirm your logo still displays correctly after replacing the certificate.
Verifying Your BIMI Setup
BIMI is configured entirely through DNS records — there is no BIMI configuration in the Lettr dashboard or API. Once you’ve added the BIMI TXT record to your DNS and ensured DMARC enforcement is in place, email clients will automatically look up and display your logo.Email Client Support
BIMI support varies by email client:| Client | VMC Required | Support Level |
|---|---|---|
| Gmail | Yes | Full support |
| Yahoo Mail | Yes | Full support |
| Apple Mail | No | Basic support |
| Fastmail | No | Basic support |
| AOL Mail | Yes | Full support |
| Microsoft Outlook | Limited | Testing phase |
BIMI adoption is still growing. Microsoft Outlook has limited support in testing, and many smaller clients don’t support BIMI at all. Gmail and Yahoo Mail are the primary clients where BIMI makes a visible difference today. Even without universal support, these two clients cover a large share of most sender audiences.
Testing Your BIMI Setup
1. Validate DNS Record
Use a DNS lookup tool to verify your BIMI record:2. Use BIMI Validators
- BIMI Inspector - bimigroup.org/bimi-generator
- BIMI Lookup - Check BIMI records and logo compliance
- MXToolbox - BIMI record validation
3. Send Test Emails
Send test emails to accounts at Gmail, Yahoo, and Apple Mail to verify logo display.Common BIMI Configurations
Basic Setup (No VMC)
For testing or clients that don’t require VMC:Production Setup (With VMC)
For full email client support:Subdomain Configuration
BIMI can be configured per subdomain:Troubleshooting
Logo not displaying
Logo not displaying
- Verify DMARC is set to
p=quarantineorp=rejectwithpct=100 - Check that the BIMI record exists at
default._bimi.yourdomain.com - Ensure logo URL is accessible via HTTPS
- Verify SVG meets Tiny PS requirements
- For Gmail/Yahoo, VMC is required
BIMI record not found
BIMI record not found
- Check DNS record is at
default._bimi.example.com(not_bimi.example.com) - Allow time for DNS propagation
- Verify record syntax is correct
SVG validation errors
SVG validation errors
- Ensure SVG uses Tiny PS profile
- Remove any scripts, animations, or external references
- Check aspect ratio is 1:1 (square)
- Verify background is solid (no transparency)
- Keep file size under 32 KB
VMC validation failing
VMC validation failing
- Ensure VMC file is accessible at HTTPS URL
- Check VMC hasn’t expired
- Verify VMC domain matches sending domain
- Confirm trademark registration is current
Logo displays inconsistently
Logo displays inconsistently
- BIMI display depends on sender reputation
- New domains may not show logos immediately
- Some clients cache logos, so changes may take time to appear
- Check that all authentication (SPF, DKIM, DMARC) is passing
BIMI Implementation Checklist
Use this checklist before launching BIMI:- DMARC policy is
p=quarantineorp=reject - DMARC percentage is
pct=100 - SPF and DKIM are verified and passing
- Logo meets SVG Tiny PS requirements
- Logo is square with solid background
- Logo file is under 32 KB
- Logo is hosted at HTTPS URL
- VMC obtained (for Gmail/Yahoo support)
- VMC hosted at HTTPS URL
- BIMI TXT record created
- Tested with BIMI validator tools
- Sent test emails to verify display
Best Practices
- Nail DMARC first - BIMI won’t work without DMARC enforcement
- Use your registered trademark - Required for VMC
- Keep logos simple - Complex logos may not render well at small sizes
- Test across clients - Verify appearance in multiple email apps
- Monitor authentication - BIMI fails if SPF/DKIM/DMARC fail
- Update gradually - Allow time for caches to refresh when changing logos
- Consider all sizes - Logos display at various sizes (32px to 100px+)