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doc/mainpage.py

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+## @mainpage Writing Milters in Python
+#
+# 
+# At the lowest level, the <code>milter</code> module provides a thin wrapper
+# around the <a href="https://www.milter.org/developers/api/index"> sendmail
+# libmilter API</a>.  This API lets you register callbacks for a number of
+# events in the process of sendmail receiving a message via SMTP.  These
+# events include the initial connection from a MTA, the envelope sender and
+# recipients, the top level mail headers, and the message body.  There are
+# options to mangle all of these components of the message as it passes through
+# the milter.
+# 
+# At the next level, the <code>Milter</code> module (note the case difference)
+# provides a Python friendly object oriented wrapper for the low level API.  To
+# use the Milter module, an application registers a 'factory' to create an
+# object for each connection from a MTA to sendmail.  These connection objects
+# must provide methods corresponding to the libmilter callback events.
+# 
+# Each event method returns a code to tell sendmail whether to proceed with
+# processing the message.  This is a big advantage of milters over other mail
+# filtering systems.  Unwanted mail can be stopped in its tracks at the
+# earliest possible point.
+# 
+# The <code>Milter.Base</code> class provides default implementations for
+# event methods that do nothing, and also provides wrappers for the libmilter
+# methods to mutate the message.  It automatically negotiates with MTA
+# which protocol steps need to be processed by the milter, based on
+# which callback methods are overridden.
+#
+# The <code>Milter.Milter</code> class provides an alternate default
+# implementation that logs the main milter events, but otherwise does nothing.
+# It is provided for compatibility.
+# 
+# The <code>mime</code> module provides a wrapper for the Python email package
+# that fixes some bugs, and simplifies modifying selected parts of a MIME
+# message.