Link domain(s)
A link domain, also called a click-tracking domain or custom tracking domain, is the domain that appears in the URLs of tracked links within marketing emails. When an email marketing platform tracks clicks, it rewrites the original URLs in your email to pass through its own tracking infrastructure before redirecting to the destination. By default, these tracking links use the email platform’s own domain. A custom link domain allows you to use your own branded domain instead, so that the URLs in your email look like they belong to your organisation.
Custom link domains improve deliverability and brand trust in two ways. Spam filters assess the reputation of every domain that appears in an email, including tracking link domains. Using a branded custom domain that shares your sending domain’s positive reputation, rather than a shared ESP domain that carries the reputation of all its users, removes a potential filtering risk. It also means that recipients who hover over links before clicking see a URL that looks like it belongs to your brand, not an unfamiliar third-party domain.
For B2B email marketers, setting up a custom link tracking domain is a one-time technical configuration task that pays ongoing dividends. It requires adding a CNAME DNS record pointing to your ESP’s tracking infrastructure. Most ESPs provide step-by-step instructions. The most common approach is to use a subdomain of your main sending domain, such as click.yourdomain.com, which benefits from your primary domain’s established reputation rather than starting fresh with a brand new domain.
Why does my ESP rewrite the links in my emails?
Email platforms rewrite links to route them through their tracking infrastructure so they can record when a recipient clicks a link. When a recipient clicks a tracked link, the request first hits the ESP’s tracking server, which logs the click event (recording which contact clicked, which link, and at what time), and then immediately redirects the recipient to the original destination URL. This happens in milliseconds and is transparent to the recipient. Without link rewriting, ESPs would have no way of tracking clicks.
What is a CNAME record and how does it relate to link domains?
A CNAME record (Canonical Name record) is a type of DNS record that creates an alias from one domain name to another. Setting up a custom link domain involves adding a CNAME record in your domain’s DNS settings that points your custom subdomain (such as click.yourdomain.com) to your ESP’s tracking servers. When a tracked link in your email is clicked, the CNAME record directs the request to your ESP’s infrastructure, which logs the click and redirects to the destination. The CNAME setup is a one-time configuration task in your domain registrar or DNS management tool.
Can having a separate link domain affect email deliverability?
Yes, in both positive and negative ways. Using a custom branded link domain that shares your sending domain’s positive reputation removes the risk of your emails being affected by the shared ESP tracking domain’s reputation. However, if your custom link domain has its own poor reputation or has no sending history at all, it can introduce a negative signal. The safest approach is to use a subdomain of your main sending domain (click.yourdomain.com rather than a completely different domain), which benefits from your primary domain’s established reputation.