Key takeaway: Open tracking on a shared domain means you inherit every other user's reputation. Point tracking at a subdomain you own, or drop open tracking entirely and measure on replies.

Open tracking is one of the most common quiet causes of poor deliverability, and almost nobody connects the two.

How tracking works, and why it hurts

To track an open, your sending tool embeds a tiny invisible image in your email. When the recipient's client loads it, the server records an open. To track a click, it rewrites your links to route through a redirect. Both mechanisms mean your email now contains a link to a tracking domain.

Here is the problem. By default, that tracking domain is your sending tool's shared domain, used by every other customer of that tool, including the reckless ones. Their spam gets your tracking domain flagged, and every email you send now contains a link to a flagged domain. You inherit their reputation.

The fix: a custom tracking domain

You point a subdomain you own, for example track.yoursendingdomain.com, at your sending tool. Now the tracking links in your emails reference your domain, and your tracking reputation is yours alone.

Setup, generally

1. In your sending tool (Instantly, Smartlead, and similar), find the custom tracking domain setting. It will give you a CNAME target.

2. In your DNS, create a CNAME record: host track (or whatever subdomain you choose), pointing at the value your tool provided.

3. Wait for DNS propagation, then verify inside the tool until it confirms the domain is connected.

4. Repeat per sending domain. Each one should track through its own subdomain, not a shared one.

The stronger option: do not track opens at all

Open tracking is increasingly unreliable anyway. Apple Mail's privacy protection pre-fetches images, inflating opens for a large share of your list, and other providers are following. You are adding a deliverability liability to collect a metric that is becoming fiction.

Many high performing senders now turn open tracking off entirely and measure on replies, which is the only number that reflects a real human doing something. If you need click data, keep click tracking on a custom domain and drop the pixel.

The rule of thumb: if you are going to track, track on a domain you own. If the metric would not change a decision you would actually make, do not track it at all, and remove the liability. Frostmailer sets up a custom tracking subdomain per sending domain so you never inherit a shared tracking reputation.

Want this done for you?

Our Build and Release service stands up your entire cold email infrastructure: domains, mailboxes, authentication, warm-up, and tracking, all authenticated and ready to send. You skip the weeks of setup and start with campaigns.

Book a call