As greylistd does not seem to be developed anymore and I wanted to have --auto-whitelist-clients I have switched to postgrey.
I am using postgrey-integration into exim4 written by Guy Antony Halse with some minor changes to minimize the differences to my greylistd setup. - I greylist on /27 instead of /24 networks and will immediately reject invalid recipients instead of greylisting them.
postgrey runs with --unix=/var/run/postgrey/socket --retry-window=4 --lookup-by-host --auto-whitelist-clients=10 --exim.
Update 2006-10-22: As found in Bug #380257 postgrey wants the querying server to pass a postfix instance parameter. This parameter identifies a single mail i.e. for one message with multiple receipients the instance identifier will stay the same. I am generating this one in exim's mail ACL.
[ in mail ACL:]
# instance parameter for postfix policy daemons, unique for every mail,
# i.e. incremented for mail from, but unchanged for rcpt to.
warn set acl_m2 = $pid.$tod_epoch.$sender_host_port
[...]
[ in rcpt ACL:]
defer
log_message = greylisted host $sender_host_address
!senders = : postmaster@*
domains = +local_domains : +relay_to_domains
!hosts = /etc/exim4/no-greylist-hosts
!authenticated = *
verify = recipient/callout=20s,use_sender,defer_ok
set acl_m3 = request=smtpd_access_policy\n\
protocol_state=RCPT\n\
protocol_name=${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{\
${readsocket{/var/run/postgrey/socket}{$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/exim4/no-greylist-hosts
!authenticated = *
message = ${sg{$acl_m3}{^\\w+\\s*}{}}
condition = ${if eq{${uc:${substr_0_7:$acl_m3}}}{PREPEND}{true}{false}}
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