Configuring sendmail, SpamAssasin and MIMEDefang First create some accounts: # /usr/sbin/groupadd -g 25 smmsp # /usr/sbin/useradd -c "sendmail MTA user" -u 25 -d /var/empty -g smmsp smmsp (ignore warning) UX: /usr/sbin/useradd: WARNING: uid 25 is reserved. # /usr/sbin/useradd -c "MIMEDefang" -u 102 -d /var/spool/MIMEDefang -g smmsp -s /bin/false defang Create the following directories: # mkdir -p /var/empty # chown root:sys /var/empty # chmod 755 /var/empty # mkdir -p /var/spool/MIMEDefang # chown defang:smmsp /var/spool/MIMEDefang # chmod 750 /var/spool/MIMEDefang # mkdir -p /var/spool/clientmqueue # chown smmsp:smmsp /var/spool/clientmqueue # chmod 770 /var/spool/clientmqueue