To configure a smart host, create /etc/exim.conf.local on the source server (server1 in this example) and add the following lines. Be sure to change to the hostname or IP of the smart host server.

You should download yumdownloader postgrey the you should extract this rpm and take some files for usage:

rpm2cpio postgrey-1.34-4.fc18.noarch.rpm | cpio -idv

the you can need copy some postgrey configuration and executable files from ./usr/sbin:

./usr/sbin/postgrey
./usr/sbin/postgreyreport

to /usr/local/sbin

./etc/postfix/postgrey_whitelist_clients.local
./etc/postfix/postgrey_whitelist_recipients
./etc/postfix/postgrey_whitelist_clients

to /etc folder

then you need create postgrey working folder for postgrey database

mkdir /var/spool/exim/postgrey && chown mailnull.mail /var/spool/exim/postgrey

to start postgrey you can like this:

/usr/local/sbin/postgrey -d –unix=/var/spool/exim/postgrey/socket –exim –syslog-facility=local6 –user=mailnull –group=mail –dbdir=/var/spool/exim/postgrey –delay=60 –max-age=35 –retry-window=12h –greylist-text=Greylisted. Please, try again later. –whitelist-clients=/etc/postgrey_whitelist_clients –whitelist-recipients=/etc/postgrey_whitelist_recipients –whitelist-clients=/etc/postgrey_whitelist_clients.local –auto-whitelist-clients=5

if you can start, you maybe missing some dependencies like:

yum install perl-BerkeleyDB perl-Net-DNS perl-Net-Server perl-Digest-HMAC perl-IO-Multiplex perl-Digest-SHA1

You should create new ACL rule in your exim.conf

begin acl

# ACL that is used after the RCPT command
check_recipient:
# postgrey [TOP]

defer
log_message = greylisted host $sender_host_address
!senders = : postmaster@*
# domains = +local_domains : +relay_to_domains
!hosts = /etc/virtual/domains
!authenticated = *
verify = recipient/callout=20s,use_sender,defer_ok
set acl_m3 = request=smtpd_access_policy\n\
protocol_state=RCPT\n\
protocol_name=${uc:$received_protocol}\n\
instance=${acl_m2}\n\
helo_name=${sender_helo_name}\n\
client_address=${substr_-3:${mask:$sender_host_address/27}}\n\
client_name=${sender_host_name}\n\
sender=${sender_address}\n\
recipient=$local_part@$domain\n\n
set acl_m3 = ${sg{\
${readsocket{ /postgrey/socket/full_address }{$acl_m3}\
{5s}{}{action=DUNNO}}\
}{action=}{}}
message = ${sg{$acl_m3}{^\\w+\\s*}{}}
condition = ${if eq{${uc:${substr{0}{5}{$acl_m3}}}}{DEFER}{true}{false}}

# add “greylisted by ..seconds” header to mail which has successfully
# passed the greylisting.
warn
!senders = : postmaster@*
# domains = +local_domains : +relay_to_domains
!hosts = /etc/virtual/domains
!authenticated = *
message = ${sg{$acl_m3}{^\\w+\\s*}{}}
condition = ${if eq{${uc:${substr_0_7:$acl_m3}}}{PREPEND}{true}{false}}

# postgrey [END]

# to block certain wellknown exploits, Deny for local domains if
# local parts begin with a dot or contain @ % ! / |
deny domains = +local_domains
local_parts = ^[.] : ^.*[@%!/|]

After this you can restart you exim server and check if you exim use greylisting.