Why do aliases not work in sendmail when the sendmail daemon is not running?

Issue

• Sendmail is configured as per this kbase to send all emails to relay mail server. Why alias doesn't work in sendmail when sendmail daemon is not running ?
• The /etc/aliases file is configured to send messages destined to  root to test@example.net but the emails are not  getting out when logwatch script is executed. After modifying /usr/share/logwatch/default.conf/logwatch.conf file and changed the MailTo line from root to test@example.net, emails are received when logwatch script is executed.