Mail domain.com

A simple one!

mail is a common subdomain used for email services, and domain.com is a generic top-level domain (gTLD). So, mail.domain.com is a fully qualified domain name (FQDN) that can be used for email services.

Here are a few possible uses for mail.domain.com:

1. Email server: mail.domain.com can be used as the hostname for an email server, such as a mail transfer agent (MTA) or a mail delivery agent (MDA).
2. Webmail interface: It can also be used as the URL for a webmail interface, allowing users to access their email accounts through a web browser.
3. Email client: Some email clients, such as Microsoft Outlook, may use mail.domain.com as the default SMTP server or IMAP/POP3 server for sending and receiving emails.

In summary, mail.domain.com is a valid FQDN that can be used for various email-related purposes.