It can be anything! An apex, subdomain, or even a URL.
Domain Name: webmail.tachi.aiDomain Status: No Object Found>>> Last update of WHOIS database: 2024-09-23T05:27:50.127Z <<<
Domain Name: webmail.tachi.ai
Domain Status: No Object Found
>>> Last update of WHOIS database: 2024-09-23T05:27:50.127Z <<<