What Is UTM Parameters?

Why It Matters

When you’re forwarding domains, you need to know which forwarded domain sent the traffic. UTM parameters solve this by tagging each redirect with tracking information that appears in Google Analytics.

UTM Parameter Types

Parameter	Purpose	Example
utm_source	Traffic source	google, twitter, old-brand-com
utm_medium	Marketing medium	redirect, email, social
utm_campaign	Campaign name	brand-migration-2024
utm_term	Search terms	domain forwarding
utm_content	Content variant	homepage-redirect

UTM Parameters with Domain Forwarding

Strategy 1: Append UTMs to destination

old-brand.com/page
  → 301 → new-brand.com/page?utm_source=old-brand&utm_medium=redirect&utm_campaign=migration

This tags every redirected visitor so you can track how much traffic your old domain still sends.

Strategy 2: Pass through existing UTMs

old-brand.com/page?utm_source=twitter&utm_medium=social
  → 301 → new-brand.com/page?utm_source=twitter&utm_medium=social

Preserves the original tracking from marketing campaigns.

Why UTM Parameters Beat Referrer Headers

The referrer header is unreliable — it changes during redirects and is blocked by some browsers. UTM parameters are part of the query string and survive redirects, making them the preferred tracking method.

Tracking Method	Survives Redirects?	Reliable?	Custom Data?
Referrer header	Sometimes	No	No
UTM parameters	Yes	Yes	Yes
Domain Forward analytics	N/A (measured at redirect)	Yes	Limited