Rspamd (https://rspamd.com/webui/) is an easy to use spam filtering tool presently installed with mailcow.

1. Go to the mailcow web admin interface
2. Click on Configuration > Debug page
3. Modify the Rspamd UI password
4. Go to https://${MAILCOW_HOSTNAME}/rspamd in a browser and log in!

Additional configuration options and documentation can be found here : https://rspamd.com/webui/