Use a custom tracking domain for links in your emails

What it means

To count clicks, newsletter and marketing tools replace every link in your email with a link to their tracking domain. The reader clicks, passes through the tool's server, then arrives on your page.

By default, this tracking domain is shared by all the tool's customers, for example click.example-provider.com. A custom tracking domain is a subdomain of yours, such as click.yourdomain.com, that points to the tool.

Why it matters

• Shared reputation. If another customer sends spam, the shared tracking domain can end up on domain blacklists like Spamhaus DBL, SURBL or URIBL, and your emails are filtered too.
• Mismatched domains look suspicious. An email from yourdomain.com whose links all go to an unknown domain looks like phishing to filters and to readers.
• Your own reputation. With your subdomain, your good sending history stays with you.

How to check

Delivmail checks this for you in two ways:

• Send a test email: on the home page (/), copy your unique test address, send it a normal email from the mailbox or tool you want to check, then open the report.
• Use the Domain scanner: type your domain at /domain-scanner to read your SPF, DMARC and MX records without sending anything.

The report lists the domains found in your links and whether any of them is on a blacklist. You can also check a domain at /blacklists.

How to fix it

1. Find the setting. In your tool, look for "custom tracking domain", "branded links", "link branding" or "click tracking domain". It is often on the same page as domain authentication.
2. Choose a subdomain. Pick something simple like click.yourdomain.com or links.yourdomain.com. Do not use your main website address.
3. Add the CNAME record. The tool gives you a value. In your DNS provider, add:

   click.yourdomain.com  CNAME  (value given by the tool)

   If your DNS panel adds the domain automatically, type only click.
4. Turn on HTTPS. Many tools offer an SSL certificate for your tracking domain. Enable it: links without HTTPS look less trustworthy and some browsers warn readers. On Cloudflare, follow the tool's instructions on proxying, as some tools require "DNS only".
5. Verify and activate. Click "Verify" in the tool, then make it the default tracking domain for your campaigns.

Other good habits

• Do not use public link shorteners (bit.ly and similar) in emails: they are often abused and filtered.
• Keep the number of links reasonable and make the visible text match where the link goes.
• For password resets and receipts, you can turn click tracking off completely.

Check that it is fixed

DNS changes can take from a few minutes to 48 hours. Send a test campaign to a new Delivmail test address. In the report, the link domains should now be your own subdomain, and none should be blacklisted. Click a link to make sure it still opens the right page over HTTPS.