Enter spamd lines in rc.conf[.local]
spamd_flags="-v -G 2:4:864" # for normal use: "" and see spamd-setup(8)
NOTE: Greylisting is enabled by default. Use spamd_black if you want to enable blacklist-only mode.
Maintenance handled with spamd-setup(8), fetches the lists you specified
Tables automatically updated, use spamdb(8)
In addition, you need rules to let legitimate email through
Other interesting options: -s # of seconds between bytes, -w window size # of bytes