From Debian package 0.0.20080702-10
0074-Add-some-comments-to-mta.te-droppable.patch

Add comments describing MTA attributes
Warning: these may be out of date, as more attributes were added in r2806,
after 0.0.20080702

Index: policy/modules/contrib/mta.te
===================================================================
--- policy/modules/contrib/mta.te.orig
+++ policy/modules/contrib/mta.te
@@ -5,11 +5,18 @@
 # Declarations
 #
 
+# attribute used for domains that act on behalf of the user to deliver mail
+# to the queue
 attribute mailcontent_type;
 attribute mta_exec_type;
 attribute mta_user_agent;
+
+# attribute used for domains that deliver mail locally
 attribute mailserver_delivery;
+
 attribute mailserver_domain;
+
+# attribute used for domains that send mail externally (smtp or lmtp)
 attribute mailserver_sender;
 
 attribute user_mail_domain;