The stock syslog.conf on OSX contains in part:
I tried changing that to:
And launching spamd with "-s local7".
The result: postfix and dovecot are logged into mail.log and not into system.log. Good. Spamd is logged into spamd.log. Good. But spamd is also logged into console.log. Bad. And I don't understand why.
Also, messages from spamd are logged slightly differently in the two files. Dunno if that's relevant, but the logs look like:
Oct 26 19:01:55 grendel org.macports.spamd:  info: prefork: child states: II
Oct 26 19:01:55 grendel spamd: prefork: child states: II
So how do I keep spamd out of system.log?
Update: The answer is, "redirect spamd's stderr to /dev/null or launchd will log it a second time." Apparently spamd spams stderr with all its logs as well as whatever the -s option says.