diff --git a/src/configure.default b/src/configure.default
index f1198b1..8f88a3b 100644
--- a/src/configure.default
+++ b/src/configure.default
@@ -124,6 +124,7 @@ acl_smtp_rcpt =         acl_check_rcpt
 acl_smtp_data_prdr =    acl_check_prdr
 .endif
 acl_smtp_data =         acl_check_data
+acl_smtp_mime =         acl_check_mime
 
 # You should not change those settings until you understand how ACLs work.
 
@@ -136,7 +137,7 @@ acl_smtp_data =         acl_check_data
 # of what to set for other virus scanners. The second modification is in the
 # acl_check_data access control list (see below).
 
-# av_scanner = clamd:/tmp/clamd
+av_scanner = clamd:/var/run/clamd.exim/clamd.sock
 
 
 # For spam scanning, there is a similar option that defines the interface to
@@ -458,7 +459,8 @@ acl_check_rcpt:
   accept  local_parts   = postmaster
           domains       = +local_domains
 
-  # Deny unless the sender address can be verified.
+  # Deny unless the sender address can be routed. For proper verification of the
+  # address, read the documentation on callouts and add the /callout modifier.
 
   require verify        = sender
 
@@ -601,21 +603,26 @@ acl_check_data:
           message =     header syntax
           log_message = header syntax ($acl_verify_message)
 
+  # Put simple tests first. A good one is to check for the presence of a
+  # Message-Id: header, which RFC2822 says SHOULD be present. Some broken
+  # or misconfigured mailer software occasionally omits this from genuine
+  # messages too, though -- although it's not hard for the offender to fix
+  # after they receive a bounce because of it.
+  #
+  # deny    condition  = ${if !def:h_Message-ID: {1}}
+  #         message    = RFC2822 says that all mail SHOULD have a Message-ID header.\n\
+  #                      Most messages without it are spam, so your mail has been rejected.
+
   # Deny if the message contains a virus. Before enabling this check, you
   # must install a virus scanner and set the av_scanner option above.
   #
   # deny    malware    = *
   #         message    = This message contains a virus ($malware_name).
 
-  # Add headers to a message if it is judged to be spam. Before enabling this,
-  # you must install SpamAssassin. You may also need to set the spamd_address
-  # option above.
+  # Bypass SpamAssassin checks if the message is too large.
   #
-  # warn    spam       = nobody
-  #         add_header = X-Spam_score: $spam_score\n\
-  #                      X-Spam_score_int: $spam_score_int\n\
-  #                      X-Spam_bar: $spam_bar\n\
-  #                      X-Spam_report: $spam_report
+  # accept  condition  = ${if >={$message_size}{100000} {1}}
+  #         add_header = X-Spam-Note: SpamAssassin run bypassed due to message size
 
   #############################################################################
   # No more tests if PRDR was actively used.
@@ -629,11 +636,40 @@ acl_check_data:
   #           condition    = ...
   #############################################################################
 
+  # Run SpamAssassin, but allow for it to fail or time out. Add a warning message
+  # and accept the mail if that happens. Add an X-Spam-Flag: header if the SA
+  # score exceeds the SA system threshold.
+  #
+  # warn    spam       = nobody/defer_ok
+  #         add_header = X-Spam-Flag: YES
+  #
+  # accept  condition  = ${if !def:spam_score_int {1}}
+  #         add_header = X-Spam-Note: SpamAssassin invocation failed
+  #
 
-  # Accept the message.
+  # Unconditionally add score and report headers
+  #
+  # warn    add_header = X-Spam-Score: $spam_score ($spam_bar)\n\
+  #                      X-Spam-Report: $spam_report
+
+  # And reject if the SpamAssassin score is greater than ten
+  #
+  # deny    condition = ${if >{$spam_score_int}{100} {1}}
+  #         message   = Your message scored $spam_score SpamAssassin point. Report follows:\n\
+  #  	    	        $spam_report
 
   accept
 
+acl_check_mime:
+
+  # File extension filtering.
+  deny message = Blacklisted file extension detected
+       condition = ${if match \
+                        {${lc:$mime_filename}} \
+                        {\N(\.exe|\.pif|\.bat|\.scr|\.lnk|\.com)$\N} \
+                     {1}{0}}
+
+  accept
 
 
 ######################################################################