Open Tracking Is Hurting Your Cold Emails. Use a Custom Tracking Domain (or Turn It Off)
Most cold email tools switch on open tracking by default. Few people question it. Yet in many of the placement problems we look at, tracking is part of the cause.
How tracking works
Open tracking adds a tiny invisible image to your email. When the recipient's mail app loads images, it requests that image from the tool's server, and the tool records an open.
Click tracking rewrites every link in your email so it goes through the tool's server first, then redirects to the real page.
Both need a domain to serve from. By default, that's the tool's shared domain, used by thousands of other senders.
Why that's a problem
When your email contains links and images from a domain that thousands of people use for cold outreach, filters judge you partly by their behaviour. If other senders on that shared domain are spamming, your emails inherit some of that reputation.
It also creates a mismatch: your email comes from yourbrand.com but contains links to track.sometool.io. That's a pattern filters notice.
Open rates aren't reliable anyway
Apple Mail Privacy Protection loads images automatically for many Apple Mail users, which records an "open" whether or not the person read anything. Some corporate security tools do the same when they scan links. Meanwhile, some mail apps block images, so real opens never register.
The result: open rates are inflated in some places and missing in others. We stopped treating them as a key number for cold email years ago. Reply rate and positive reply rate are what matter.
Option 1: Turn open tracking off
For first-touch cold emails, this is what we usually recommend. One less image, one less external domain, and a plain-text feel that reads like a real person wrote it.
Keep click tracking off too unless you really need it. A first cold email usually shouldn't have a link at all.
Option 2: Use a custom tracking domain
If you need tracking, for a client report or for follow-up logic, set up a custom tracking domain:
- Pick a subdomain of your outreach domain, such as
link.tryyourbrand.com - Add the CNAME record your tool provides
- Turn on SSL for it in the tool, if available
- Confirm in a test email that links and the pixel use your subdomain
Now tracking requests go through a domain that matches your sender and only carries your own reputation.
What we track instead
- Replies, and whether they're positive, neutral or negative
- Meetings booked
- Bounces and unsubscribes
- Inbox placement, measured with seed tests rather than guessed from opens
Related reading
- Why your cold emails are going to spam
- Spam trigger words: the myth
- Cold email copy that gets replies
Every Nestmarketing setup includes custom tracking domains for clients who need them.