this is how to enable for all user via bash script
Just use as reference. you can simple to edit directly files relate to spamassassin.
perl -pi -e
command or a sed command.sed -i 's/5/7\.5/g' /home/*/.spamassassin/user_prefs
sed -i 's/5/7\.5/g' /root/user_prefs
sed -i 's/required_score.*/required_score 7\.5/' /home/*/.spamassassin/user_prefs