Email tends to be one of the most profitable channels — and one of the worst measured. Without proper tagging and identification, newsletter conversions get credited to "direct" or another channel. Here's how to measure email accurately.
Why email is tricky to measure
- Missing UTMs. Without UTM parameters in the links, analytics doesn't know the visit came from email.
- Lost identity. Between the email click and a purchase a few days later, a client-side cookie can expire (ITP) — and the conversion detaches.
- Opening across devices. People read email on mobile, buy on desktop.
How to do it
- 1. Tag UTMs rigorously. Every link in the email:
utm_source=newsletter&utm_medium=email&utm_campaign=…. Without it, measurement doesn't stand. - 2. Ensure longer identification. Server-set first-party cookies last beyond ITP's 7-day cap, so a longer journey from email stays connected. See ITP and lost conversions.
- 3. Capture the conversion reliably. Server-side captures it even through ad-blockers, so email gets credit for what it really drove.
- 4. Connect the signed-in user. If the customer buys signed in, a user_id connects reading on mobile and buying on desktop — see what client_id and user_id are.
What to watch
Opens and clicks in the email are measured by your email tool; the on-site conversion after the click is measured by your tracking. UTMs connect them. When a UTM is missing or lost in a redirect, attribution falls apart.
Summary
You'll measure email accurately when you tag UTMs rigorously and have reliable, long-lived identification — which server-side tracking provides. Then email gets credited with the revenue it really drove. More in conversion attribution.