Enter spamd lines in rc.conf[.local]
spamd_flags="-v -G 2:4:864" # for normal use: "" and see spamd-setup(8) spamd_grey=YES # use spamd greylisting if YES
NOTE: OpenBSD 4.1 onwards: greylisting enabled by default. Use spamd_black 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