Normally, the default configuration is standalone.
GREY_MODE STANDALONE GREY_SOCKET local:/var/jchkmail/j-greyd.sock
But when you use several frontend equal MX servers to get the internet traffic, you will get traffic balanced between all. It's then necessary to add a daemon on a server to share the greylist database between all.
Have also a look here
j-greyd can be configured in three different ways :
j-chkmail.cf
GREY_LOG_FILE file:j-grey-expire GREY_MIN_DELAY_NORMAL 10m GREY_MIN_DELAY_NULLSENDER 10m GREY_MAX_DELAY_NORMAL 3d GREY_MAX_DELAY_NULLSENDER 6h GREY_VALIDLIST_LIFETIME 1w GREY_WHITELIST_LIFETIME 2w GREY_BLACKLIST_LIFETIME 1d GREY_PENDING_NORMAL 1000 GREY_PENDING_NULLSENDER 1000 GREY_IP_COMPONENT NET GREY_FROM_COMPONENT HOST GREY_TO_COMPONENT FULL GREY_CLEANUP_INTERVAL 10m GREY_DEWHITE_FLAGS DomainMatch
j-chkmail.cf
GREYD_SOCKET_LISTEN inet:2015@0.0.0.0 GREYD_LOG_FACILITY local6 GREYD_LOG_LEVEL 10 GREYD_PID_FILE /var/run/jchkmail/j-greyd.pid GREYD_CLIENT_IDLE_MAX 300