--- exim-4.66/src/configure.default.grey	2007-02-07 13:07:40.000000000 +0000
+++ exim-4.66/src/configure.default	2007-02-08 10:16:17.000000000 +0000
@@ -105,6 +105,7 @@ hostlist   relay_from_hosts = 127.0.0.1
 # manual for details. The lists above are used in the access control lists for
 # checking incoming messages. The names of these ACLs are defined here:
 
+acl_smtp_mail = acl_check_mail
 acl_smtp_rcpt = acl_check_rcpt
 acl_smtp_data = acl_check_data
 acl_smtp_mime = acl_check_mime
@@ -318,6 +319,29 @@ timeout_frozen_after = 7d
 
 begin acl
 
+
+# This access control list is used for the MAIL command in an incoming
+# SMTP message.
+
+acl_check_mail:
+
+  # Hosts are required to say HELO (or EHLO) before sending mail.
+  # So don't allow them to use the MAIL command if they haven't
+  # done so.
+
+  deny condition = ${if eq{$sender_helo_name}{} {1}}
+       message = Nice boys say HELO first
+
+  # Use the lack of reverse DNS to trigger greylisting. Some people
+  # even reject for it but that would be a little excessive.
+  
+  warn condition = ${if eq{$sender_host_name}{} {1}}
+       set acl_m_greylistreasons = Host $sender_host_address lacks reverse DNS\n$acl_m_greylistreasons
+  
+  accept
+
+
+
 # This access control list is used for every RCPT command in an incoming
 # SMTP message. The tests are run in order until the address is either
 # accepted or denied.
@@ -435,7 +459,8 @@ acl_check_rcpt:
   # There are no default checks on DNS black lists because the domains that
   # contain these lists are changing all the time. However, here are two
   # examples of how you can get Exim to perform a DNS black list lookup at this
-  # point. The first one denies, whereas the second just warns.
+  # point. The first one denies, whereas the second just warns. The third
+  # triggers greylisting for any host in the blacklist.
   #
   # deny    message       = rejected because $sender_host_address is in a black list at $dnslist_domain\n$dnslist_text
   #         dnslists      = black.list.example
@@ -443,6 +468,10 @@ acl_check_rcpt:
   # warn    dnslists      = black.list.example
   #         add_header    = X-Warning: $sender_host_address is in a black list at $dnslist_domain
   #         log_message   = found in $dnslist_domain
+  #
+  # warn    dnslists      = black.list.example
+  #         set acl_m_greylistreasons = Host found in $dnslist_domain\n$acl_m_greylistreasons
+  #
   #############################################################################
 
   #############################################################################
@@ -456,6 +485,10 @@ acl_check_rcpt:
   # require verify = csa
   #############################################################################
 
+  # Alternatively, greylist for it:
+  # warn !verify = csa
+  #      set acl_m_greylistreasons = Host failed CSA check\n$acl_m_greylistreasons
+
   # At this point, the address has passed all the checks that have been
   # configured, so we accept it unconditionally.
 
@@ -481,6 +514,12 @@ acl_check_data:
   # deny    condition  = ${if !def:h_Message-ID: {1}}
   #         message    = RFC2822 says that all mail SHOULD have a Message-ID header.\n\
   #                      Most messages without it are spam, so your mail has been rejected.
+  #
+  # Alternatively if we're feeling more lenient we could just use it to 
+  # trigger greylisting instead:
+
+  warn    condition  = ${if !def:h_Message-ID: {1}}
+          set acl_m_greylistreasons = Message lacks Message-Id: header. Consult RFC2822.\n$acl_m_greylistreasons
 
   # Deny if the message contains a virus. Before enabling this check, you
   # must install a virus scanner and set the av_scanner option above.
@@ -515,8 +554,30 @@ acl_check_data:
   #         message   = Your message scored $spam_score SpamAssassin point. Report follows:\n\
   #  	    	        $spam_report
 
+  # Trigger greylisting (if enabled) if the SpamAssassin score is greater than 0.5
+  #
+  # warn    condition = ${if >{$spam_score_int}{5} {1}}
+  #         set acl_m_greylistreasons = Message has $spam_score SpamAssassin points\n$acl_m_greylistreasons
+
+
+  # If you want to greylist _all_ mail rather than only mail which looks like there
+  # might be something wrong with it, then you can do this...
+  #
+  # warn set acl_m_greylistreasons = We greylist all mail\n$acl_m_greylistreasons
+
+  # Now, invoke the greylisting. For this you need to have installed the exim-greylist
+  # package which contains this subroutine, and you need to uncomment the bit below
+  # which includes it too. Whenever the $acl_m_greylistreasons variable is non-empty,
+  # greylisting will kick in and will defer the mail to check if the sender is a
+  # proper mail which which retries, or whether it's a zombie. For more details, see
+  # the exim-greylist.conf.inc file itself.
+  #
+  # require acl = greylist_mail
+
   accept
 
+# To enable the greylisting, also uncomment this line: 
+# .include /etc/exim/exim-greylist.conf.inc
 
 acl_check_mime: