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LFCS · Question #473
LFCS Question #473: Real Exam Question with Answer & Explanation
The correct answer is B: Set up a ruleset for this in /etc/sendmail.cf. To prevent unauthorized mail relaying through your Sendmail server, you must configure relay control rules within its main configuration file.
Submitted by jakub_pl· Apr 18, 2026Service Configuration
Question
To avoid spammers using your mail server to relay their messages, you need to _______.
Options
- ADisable the relay control in /etc/aliases
- BSet up a ruleset for this in /etc/sendmail.cf
- CSet up relay control in your DNS's MX record.
- DRecompile sendmail with the -NORELAY flag.
Explanation
To prevent unauthorized mail relaying through your Sendmail server, you must configure relay control rules within its main configuration file.
Common mistakes.
- A. /etc/aliases maps email addresses to local users, files, or programs, and does not provide controls for mail relaying.
- C. DNS MX records specify which mail servers are responsible for a domain, but they do not configure the relaying policies of the mail server itself.
- D. Recompiling Sendmail with a -NORELAY flag is an outdated and impractical method; relay control is managed through runtime configuration within sendmail.cf.
Concept tested. Sendmail relay control configuration
Reference. https://www.sendmail.com/doc/html/m4.html
Topics
#Mail Server Configuration#Sendmail#Spam Prevention#Relay Control
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