Another (better ?) solution :
With exim, you can for example use a blacklist (dnslists)
* bl.spamcop.net : sbl-xbl.spamhaus.org : list.dsbl.org
seems to be enough to block most spammers
// acl rule in exim.conf
// spammer listed rejected with message
drop message = $sender_host_address is blacklisted at $dnslist_domain\n$dnslist_text
!authenticated = *
dnslists = ${lookup{${lc:$local_part@$domain}}lsearch*@{/etc/virtual/dnslists}}
delay = 20s
// end acl
For me this work very well with spamassassin.
(Spamblocker never worked on my server)
I have very few % of spam.
I'm not sure that autobl is a good thing and work well.
