It can be anything! An apex, subdomain, or even a URL.
Domain Name: mail.ux.htDomain Status: No Object Found>>> Last update of WHOIS database: 2024-09-23T09:12:06.484Z <<<
Domain Name: mail.ux.ht
Domain Status: No Object Found
>>> Last update of WHOIS database: 2024-09-23T09:12:06.484Z <<<