[exim] Backup MX and Greylisting

Hello,

I'm using exim 4.66 within a freebsd jail for backup mx purposes.
Everything works fine for a couple of months. But now I want to use
greylisting to reduce the amount of spam.

I implemented "Poor Man's Simple Greylisting" by Michael Peek with these
lines in my configure file:

--snip--
# Greylisting
perl_at_start = true
perl_startup = do '/usr/local/sbin/exim_greylister'

[...]

acl_check_data:

  # Greylisting
  defer
          condition = ${if
eq{1}{${perl{greylist}{$sender_host_address}{$sender_address}{$local_part@$domain}
} }{true}{false}}
          message = Deferred RCPT: Temporary error, please try again later
          log_message = Deferred RCPT: Greylisted:
IP=$sender_host_address, Sender=$sender_address, Rcpt=$local_part@$domain
--snap--

When testing this with exim -bh <ip> I can see a false return statement
from the greylister-script. But it seems that exim does not regard this
because it won't defer the mail but accept it!


Is there anything else I have to configure?

Thank you for your help!

Regards,

Falk