[CentOS] dovecot + pigeonhole on CentOS-7

I've everything running fine under CentOS-7, as far as I can tell, except that spam is not being diverted to my spam folder ~/Maildir/.Spam . I'm running postfix + spamass-milter + spamass-milter-postfix + dovecot (+ spamassassin), and spam is being duly marked before ending in my inbox .

As far as I can see, the current advice is to leave filtering to dovecot, using the dovecot-pigeonhole rpm.

I'm wondering if anyone else is doing this? If so, what settings exactly did you use? I haven't been able to find any clear documentation, or rather I have seen widely differing instructions. My brief attempt failed, so if anyone can help I should be very grateful.

(Or if anyone has a better spam filtering scheme ...)