Custom Tracking Domains is a 📝Resend feature that routes email open and click tracking through a sender-owned domain instead of a shared Resend domain, improving deliverability and brand consistency.
Standard email tracking relies on shared infrastructure — meaning reputation is pooled across all senders on that domain. Poor sending behavior by others on a shared tracking domain can degrade deliverability for everyone. Custom tracking domains isolate reputation by running all tracking events through a subdomain the sender controls, typically configured as links.yourdomain.com via a single DNS record added in the Resend Domains dashboard.
Resend supports two tracking mechanisms, both disabled by default and configured at the domain level. Click tracking wraps each link in a redirect that logs the click event before forwarding the recipient to the original URL. Open tracking embeds a 1x1 transparent pixel; when a mail client downloads it, Resend records an open event. Both can be enabled via the dashboard or the API using the openTracking, clickTracking, and trackingSubdomain parameters on resend.domains.create(). Inbox providers favor alignment between sending domain and link domains — custom tracking satisfies that signal while also ensuring recipients never see an unfamiliar domain in the URLs they click.
The feature pairs directly with 📝Automations and webhooks: every open and click fires a real-time event usable for audience segmentation, performance measurement, and sequence branching.
For MythOS and One Inc email flows, enabling custom tracking on owned domains is a baseline hygiene step — the deliverability upside compounds with volume, and it's free to configure now.