Tracking Domains

A tracking domain is a custom subdomain used for click tracking links and open tracking pixels in your emails. Instead of using Lettr’s default tracking URLs, you can configure your own branded domain like links.yourcompany.com. Setting up a tracking domain improves recipient trust, maintains brand consistency, and can help with deliverability since links point to your own domain rather than a third-party service.

Why Use Custom Tracking Domains?

By default, tracking links in your emails use Lettr’s domain:

https://track.lettr.dev/c/abc123

With a custom tracking domain, links use your brand:

https://links.yourcompany.com/c/abc123

Benefits

Brand Consistency - Links show your domain, reinforcing brand recognition
Improved Trust - Recipients are more likely to click familiar links
Better Deliverability - Some spam filters favor custom tracking domains
Professional Appearance - Emails look more polished and legitimate

Default vs Custom Tracking

Feature	Default	Custom
Click links	`track.lettr.dev/c/...`	`links.example.com/c/...`
Open pixels	`track.lettr.dev/o/...`	`links.example.com/o/...`
SSL	Automatic	Automatic
Setup	None required	DNS configuration

Adding a Tracking Domain

Via Dashboard

Navigate to Tracking Domains

Go to Domains → Tracking in your dashboard.

Add Domain

Click Add Domain and enter your tracking subdomain (e.g., links.example.com).

Add DNS Records

Add the provided DNS records to your domain. You’ll need:

A CNAME record pointing to Lettr’s tracking server
TXT records for SSL certificate validation

Verify Domain

Click Verify to check DNS configuration and provision your SSL certificate.

Tracking domains are managed through the Lettr dashboard. API endpoints for tracking domains are not currently available.

DNS Configuration

After adding your tracking domain, configure these DNS records:

CNAME Record

Points your subdomain to Lettr’s tracking servers:

Field	Value
Type	CNAME
Name	`links` (your chosen subdomain)
Value	`proxy.lettr-tracking.com`

SSL Validation TXT Record

Required for automatic SSL certificate provisioning:

Field	Value
Type	TXT
Name	`_acme-challenge.links`
Value	(provided by Lettr)

Ownership TXT Record

Verifies domain ownership:

Field	Value
Type	TXT
Name	`_cf-custom-hostname.links`
Value	(provided by Lettr)

The exact TXT record values are unique to your domain and will be provided when you add your tracking domain. Copy them exactly as shown.

Choosing a Subdomain

Common choices for tracking subdomains:

Subdomain	Full Domain
`links`	`links.example.com`
`track`	`track.example.com`
`click`	`click.example.com`
`go`	`go.example.com`
`e`	`e.example.com`

Keep the subdomain short and generic. Avoid words like “tracking” or “analytics” that might trigger spam filters.

SSL Certificates

Lettr automatically provisions and renews SSL certificates for your tracking domain. This ensures all tracking links use HTTPS.

Certificate Status

Status	Description
`active`	SSL certificate provisioned and active
`pending`	Certificate being provisioned
`pending_validation`	Waiting for TXT record validation
`initializing`	Initial setup in progress

SSL provisioning typically completes within a few minutes after DNS verification.

Verifying Your Tracking Domain

Via Dashboard

Go to Domains → Tracking
Find your domain and click Verify
Wait for both CNAME and SSL verification to complete

Tracking Domain Status

Status	Description	CNAME	SSL
`active`	Fully verified and operational	Valid	Active
`pending_cname`	Waiting for CNAME verification	Pending	Active
`pending_ssl`	Waiting for SSL certificate	Valid	Pending

Linking to a Sending Domain

Associate your tracking domain with a sending domain so all emails from that domain use your custom tracking links:

Via Dashboard

Go to Domains → Sending
Select your sending domain
Choose your tracking domain from the dropdown

SSL and Deliverability

Lettr uses SSL for all tracking and automatically provisions and renews SSL certificates for your custom tracking domain. You do not need to buy or upload certificates—once both CNAME records (SSL and Proxy) are in place and verified, Lettr issues and renews the certificate. Why this matters for deliverability: Tracking links served over HTTPS from your own domain are trusted more by spam filters and look correct to recipients. Insecure or third-party tracking URLs can hurt deliverability. With automatic SSL, your tracking domain is always HTTPS and aligned with best practices.

SSL provisioning usually finishes within a few minutes after DNS verification. Until then, tracking may use Lettr’s default domain. Check the domain status in the dashboard for SSL state.

Using Custom Tracking

Once configured, all tracking automatically uses your custom domain. No code changes needed.

Click Tracking

When you enable click tracking, links in your email: Original link in your email:

<a href="https://example.com/offer">View Offer</a>

Link in delivered email (with tracking):

<a href="https://links.example.com/c/abc123">View Offer</a>

When clicked, the recipient is redirected to https://example.com/offer and the click is recorded.

Open Tracking

When you enable open tracking, a tracking pixel is added:

<img src="https://links.example.com/o/xyz789" width="1" height="1" />

Enabling Tracking in Emails

Enable tracking when sending emails:

curl -X POST https://app.lettr.com/api/emails \
  -H "Authorization: Bearer lttr_xxxxxxxxxxxx" \
  -H "Content-Type: application/json" \
  -d '{
    "from": "hello@example.com",
    "to": ["recipient@example.com"],
    "subject": "Check out our new features",
    "html": "<p>Click <a href=\"https://example.com/features\">here</a> to learn more.</p>",
    "options": {
      "click_tracking": true,
      "open_tracking": true
    }
  }'

Delete a Tracking Domain

Deleting a tracking domain will cause tracking links in previously sent emails to stop working. Recipients clicking those links will see an error.

Via Dashboard

Go to Domains → Tracking
Find the domain and click Delete
Confirm deletion

Troubleshooting

CNAME not verified

Verify the CNAME record is pointing to proxy.lettr-tracking.com
Check that you added the record to the correct subdomain
DNS propagation can take up to 48 hours, though usually completes in minutes
Some DNS providers require the full domain in the name field (e.g., links.example.com instead of links)

SSL certificate pending

Ensure both TXT records are added correctly
TXT record values must match exactly (including any trailing characters)
Certificate provisioning can take up to 24 hours in rare cases
If stuck, try removing and re-adding the tracking domain

Tracking links not using custom domain

Verify the tracking domain is linked to your sending domain
Check that tracking domain status is active
Only emails sent after configuration will use the custom domain

Certificate renewal issues

SSL certificates auto-renew before expiration
If renewal fails, check that TXT records are still in place
Contact support if certificates expire unexpectedly

Changing your tracking domain won’t affect previously sent emails. Only new emails will use the updated tracking domain.

Best Practices

Use a dedicated subdomain - Don’t use your root domain for tracking
Keep subdomains short - Shorter URLs look cleaner in emails
Avoid suspicious words - Skip words like “tracking” or “click” in the subdomain
Set up before sending - Configure tracking domains before email campaigns
Monitor SSL status - Ensure certificates stay active

Sending Domains

Configure domains for sending

Tracking

Learn about click and open tracking

Analytics

View tracking analytics

Storage Domains

Custom domains for email assets

Documentation

Quickstart

Learn

Integrations

Tracking Domains

Why Use Custom Tracking Domains?

Benefits

Default vs Custom Tracking

Adding a Tracking Domain

Via Dashboard

DNS Configuration

CNAME Record

SSL Validation TXT Record

Ownership TXT Record

Choosing a Subdomain

SSL Certificates

Certificate Status

Verifying Your Tracking Domain

Via Dashboard

Tracking Domain Status

Linking to a Sending Domain

Via Dashboard

SSL and Deliverability

Using Custom Tracking

Click Tracking

Open Tracking

Enabling Tracking in Emails

Delete a Tracking Domain

Via Dashboard

Troubleshooting

Best Practices

Sending Domains

Tracking

Analytics

Storage Domains

Documentation

Quickstart

Learn

Integrations

​Why Use Custom Tracking Domains?

​Benefits

​Default vs Custom Tracking

​Adding a Tracking Domain

​Via Dashboard

​DNS Configuration

​CNAME Record

​SSL Validation TXT Record

​Ownership TXT Record

​Choosing a Subdomain

​SSL Certificates

​Certificate Status

​Verifying Your Tracking Domain

​Via Dashboard

​Tracking Domain Status

​Linking to a Sending Domain

​Via Dashboard

​SSL and Deliverability

​Using Custom Tracking

​Click Tracking

​Open Tracking

​Enabling Tracking in Emails

​Delete a Tracking Domain

​Via Dashboard

​Troubleshooting

​Best Practices

​Related Topics

Sending Domains

Tracking

Analytics

Storage Domains

Why Use Custom Tracking Domains?

Benefits

Default vs Custom Tracking

Adding a Tracking Domain

Via Dashboard

DNS Configuration

CNAME Record

SSL Validation TXT Record

Ownership TXT Record

Choosing a Subdomain

SSL Certificates

Certificate Status

Verifying Your Tracking Domain

Via Dashboard

Tracking Domain Status

Linking to a Sending Domain

Via Dashboard

SSL and Deliverability

Using Custom Tracking

Click Tracking

Open Tracking

Enabling Tracking in Emails

Delete a Tracking Domain

Via Dashboard

Troubleshooting

Best Practices

Related Topics