It can be anything! An apex, subdomain, or even a URL.
Domain Name: www.mail.rem.msDomain Status: No Object Found>>> Last update of WHOIS database: 2024-09-23T08:17:43.386Z <<<
Domain Name: www.mail.rem.ms
Domain Status: No Object Found
>>> Last update of WHOIS database: 2024-09-23T08:17:43.386Z <<<