Install and use Spamassassin and amavis
filtres in Roundcube
In main.inc.php, go to the plugin array and add ('mamangesieve').
Then you should have a filter entry in the preference menu. Have to configure Dovecot to have it usable.
systemctl enable spamd.service systemctl start spamd.service systemctl status spamd.service
If I understand well, spamassassin just add a "spam" tag to the mail but do not remove nor move anything, which is good.
The filtering can be made by Dovecot
Install amavis-new with yast. The config file is
I read "Just use amavis with postfix. Amavis will take care of spamassassin"