+-----------------------------------------------------------------------
| filter-rspamd setup
+-----------------------------------------------------------------------

To use the rspamd filter, you must declare it first in your OpenSMTPD 
configuration.

Edit the @PKG_SYSCONFDIR@/smtpd/smtpd.conf file to declare the filter:

  filter "rspamd" \
  	 proc-exec "@PREFIX@/libexec/opensmtpd/filter-rspamd"

Then add the filter to each listener that should be filtered:

  listen on socket filter "rspamd"
  listen on $ipv4 [...] filter "rspamd"

See filer-rspamd(8) man page.

The filter itself doesn't have a configuration and depends upon 
the Rspamd daemon configuration.