# - max_age: number (default: 30 * 3600)
# lifetime of a greylist/whitelist session: ie, if a client does ne reappear during
# max_age seconds, the entries associated to this client are invalidated.
+# - cleanup_period: number (default: 86400)
+# minimum time between two cleanup of the database. You must keep in mind that cleanup
+# is important since it remove useless entries from the database and thus help
+# speeding up the lookups. A cleanup can take a few minutes if the database contains
+# a lot of entries.
# Return value:
# - if the client is whitelisted, returns whitelist
# - if the client is greylisted, returns greylist