HTTP error 404 when managing mailing list with service subdomain

Symptoms

When attempting to manage a mailing list after logging into cPanel with a service subdomain you get an HTTP error 404. 

Cause

This is being caused by a redirect to the server hostname that is only occurring when using the service subdomain. We have case CPANEL-57589 in with our developers to investigate this issue. 

Resolution

Access cPanel directly with the server's hostname or IP address and by using the relevant ports.