If you can’t or don’t want to use Content Delivery Networks when setting up SSL for click and open tracking, then you can setup custom SSL configuration.

Before Adding a Custom SSL configuration, you need to set up a valid email link whitelabel on your account like this:

Email Links Whitelabel

To add a custom SSL configuration:

  1. Prepare a proxy (like web application, nginx, or Amazon API Gateway) to take all traffic for mailing.example.com and forward it to sendgrid.net.
  2. Set up the proxy to use HTTP or HTTPS. For HTTPS, provide valid SSL certificate for mailing.example.com domain.
  3. To forward traffic, set Host HTTP header to mailing.example.com domain.
  4. Point the CNAME record to your proxy. For example, CNAME mailing.example.com proxy.example.com.
Don't validate the DNS record more than once, because after changing the CNAME, a second validation fails and the whitelabel stops working.

1. Contact SendGrid support to enable SSL click and open tracking.