To avoid spammers using your mail server to relay their messages, you need to _______.

/etc/aliases is used to create mail aliases (e.g., root: [email protected]), not to control mail relaying functionality.

For Sendmail, preventing unauthorized relaying (where spammers use your server to send their spam) is controlled by setting up relay rules in the main configuration file, /etc/sendmail.cf. These rules specify which domains or IP addresses are allowed to relay mail through your server.

An MX (Mail Exchanger) record in DNS points to the mail servers responsible for receiving mail for a domain; it does not control relaying from your server, only where incoming mail for your domain should go.

Recompiling Sendmail with a specific flag like -NORELAY is not the standard or practical way to manage relay control. Relay configurations are typically handled at runtime via the configuration file.