greylist ACL

# this acl returns either deny or accept
# since we use it inside a defer with acl = greylist_acl,
# accepting here makes the condition TRUE thus deferring,
# denying here makes the condition FALSE thus not deferring
  # For regular deliveries, check greylist.

  # check greylist tuple, returning "accepted", "deferred" or "unknown"
  # in acl_m8, and the record id in acl_m9

  warn set acl_m7 = $sender_host_address
  warn set acl_m7 = ${lookup mysql{GREYLIST_CLASS_LOOKUP}{$value}{$sender_host_address}}

  warn set acl_m8 = ${lookup mysql{GREYLIST_TEST}{$value}{result=unknown}}
       # here acl_m8 = "result=x id=y"

       set acl_m9 = ${extract{id}{$acl_m8}{$value}{-1}}
       # now acl_m9 contains the record id (or -1)

       set acl_m8 = ${extract{result}{$acl_m8}{$value}{unknown}}
       # now acl_m8 contains unknown/deferred/accepted

  # check if we know a certain triple, add and defer message if not
       # if above check returned unknown (no record yet)
       condition = ${if eq{$acl_m8}{unknown}{1}}
       # then also add a record
       condition = ${lookup mysql{GREYLIST_ADD}{yes}{no}}

  # now log, no matter what the result was
  # if the triple was unknown, we don't need a log entry
  # (and don't get one) because that is implicit through
  # the creating time above.
  warn condition = ${lookup mysql{GREYLIST_LOG}}

  # check if the triple is still blocked
       # if above check returned deferred then defer
       condition = ${if eq{$acl_m8}{deferred}{1}}
       # and note it down
       condition = ${lookup mysql{GREYLIST_DEFER_HIT}{yes}{yes}}

  # use a warn verb to count records that were hit
  warn condition = ${lookup mysql{GREYLIST_OK_COUNT}}

  # use a warn verb to set a new expire time on automatic records,
  # but only if the mail was not a bounce, otherwise set to now().
  warn !senders = :
       condition = ${lookup mysql{GREYLIST_OK_NEWTIME}}
  warn senders = :
       condition = ${lookup mysql{GREYLIST_OK_BOUNCE}}