It can be anything! An apex, subdomain, or even a URL.
Domain Name: mail.trf.aiDomain Status: No Object Found>>> Last update of WHOIS database: 2024-09-22T15:16:53.400Z <<<
Domain Name: mail.trf.ai
Domain Status: No Object Found
>>> Last update of WHOIS database: 2024-09-22T15:16:53.400Z <<<