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Tracking domain

A tracking domain is a branded hostname on your sending domain that serves open and click tracking. With it in place, the links Bird rewrites for click tracking point at your own hostname over HTTPS instead of a generic Bird domain — better-looking to recipients, and it keeps link reputation tied to your brand. Unlike the bounce domain, it's optional: it gates branded tracking, never sending.

The record

The tracking domain is a CNAME under your sending domain that resolves to Bird's tracking infrastructure in your region:
TypeHostValue
CNAMElinks.example.com<region>.links.bird.com
The value is region-specific (us1.links.bird.com or eu1.links.bird.com) — copy it from the dashboard or the domain resource. The host defaults to links. under your sending domain.

Customizing the hostname

Choose the label when you register the domain by passing tracking.name; Bird composes the full hostname:
Code example
curl -s https://us1.platform.bird.com/v1/email/domains \
  -H "Authorization: Bearer $BIRD_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "domain": "mail.acme.com",
    "tracking": { "name": "click" }
  }'
That registers click.mail.acme.com as the tracking host instead of the default links.mail.acme.com. Like the return-path, it's a per-workspace choice. Sending a tracking: null on a PATCH removes the tracking domain — sending is unaffected, only branded tracking stops.

It doesn't gate sending

A domain with verified DKIM, return-path, and DMARC can send even with no tracking record at all — capabilities.tracking is reported separately from capabilities.sending. Until the tracking CNAME verifies, opens and clicks simply aren't tracked through your branded host; nothing about delivery changes.
Tracking is the AND of three things, so a verified tracking domain alone doesn't turn tracking on:
  1. The per-send flag — track_opens / track_clicks on the message (both default true).
  2. The domain setting — settings.open_tracking / settings.click_tracking (both default off; enabling one with no tracking domain configured returns 409).
  3. A verified tracking CNAME.
So opens and clicks start flowing only once you've configured and verified a tracking domain and flipped the domain setting on. See tracking & metrics for what each flag does to a message.

Changing it later

Tracking-hostname changes are staged the same way return-path changes are: a hostname that's already verified is never replaced by an unverified one. Bird verifies the new tracking CNAME alongside the active one and promotes it only once the new record checks out, so branded tracking never breaks mid-change.
A tracking hostname is claimed by one organization per region — another org can't register the same tracking host while you hold it. If you stop using a hostname and want to free it for reuse, release it from your workspace once your replacement has verified.

Next steps