Why use a custom domain for tracking links?

Most ESPs wrap every link in your email through their own tracking domain. So that innocent-looking button in your campaign? It probably points to something like t.random-esp-domain.com before it ever reaches your subscriber's destination. That's fine by default, but it comes with a catch.

A custom tracking domain is a subdomain you own (like click.yourbrand.com) that you point to your ESP's tracking servers via a CNAME record. Your ESP still handles the redirect and counts the click. The only difference is that recipients see your domain in the URL, not your ESP's.

That difference matters more than it sounds.

Reputation isolation. Your ESP's default tracking domain is shared across every sender on that platform. If one bad actor gets it blocklisted, your click tracking breaks too, even if you've done nothing wrong. Your own subdomain keeps your reputation separate from everyone else's behavior.

Cleaner spam filter signals. Spam filters look at all the domains in an email, not just the From address. When your From address says captain@deepcurrent.io but every link runs through t.random-esp-domain.com, that mixed signal can raise flags. Keeping your own domain consistent throughout the message looks a lot more legitimate.

Better click-through rates. When someone hovers over a link and sees your domain, it reads as familiar and safe. An unfamiliar third-party domain can spook people into not clicking. (It's a small thing, but it adds up.)

Setup takes about 15 minutes. You add a CNAME record in your DNS pointing your subdomain to your ESP's tracking server, then enable it in your ESP settings. Most major platforms like Mailchimp, Klaviyo, and Twilio SendGrid support it. Some include it on all plans, others gate it behind paid tiers.

The honest downside? It's one more DNS record to manage, and if you switch ESPs you'll need to update it. That's genuinely the whole list of extra work. For most senders, the deliverability upside is worth it.

Not sure if your current tracking setup is hurting you? Our free Email Header Analyzer can show you exactly which domains are showing up in your sent emails.