The start/stop script has been placed in $PREFIX/etc/rc.d/rbl-milter.sh
Run the program now with the start command to get rbl-milter running.
By default, it uses the relays found at relays.ordb.org but you can
change that by modifying the script.  It accepts multiple -d commands
for multiple site checks.

Note that you will need to edit the proper sendmail.mc file in your
/etc/mail directory so that sendmail will pass mail to rbl-milter.
If you have not done this before, do the following:

  cd /etc/mail
  cp -p freebsd.mc `hostname`.mc

Add the INPUT_MAIL_FILTER line to the file:

  INPUT_MAIL_FILTER(`rbl-milter',`S=local:/var/run/rbl-milter')

and rebuild it

  make
  make install
  make restart

By default, the INPUT_MAIL_FILTER line will ignore the filter if
rbl-milter is not running.