It isn’t really possible to run an email server without a spam filter these days – there is just too much spam. Spam Assassin does the job very well, even with just its default configuration. Once exim is configured to use it, configuration of Spam Assassin itself is easy.

srv/salt/spam-assassin.sls

# Install and configure Spam Assassin
spamassassin:
  pkg:
    - installed
  service.running:
    - enable: True

# Client for exim to use to connect to Spam Assassin
spamc:
  pkg:
    - installed

# No custom configuration files required