<HTML> <HEAD> <TITLE>Filtering Mail with Sendmail</TITLE> </HEAD> <BODY> <!-- $Id: index.html,v 1.14 2013-11-22 20:51:39 ca Exp $ --> <H1>Filtering Mail with Sendmail</H1> <!-- <P><B>Disclaimer</B>: This preliminary API description is provided for review only. This specification may change based on feedback from reviewers, and does not bind Sendmail to offer this functionality in any release. --> <H2>Introduction</H2> <P> Sendmail's Content Management API (milter) provides third-party programs to access mail messages as they are being processed by the Mail Transfer Agent (MTA), allowing them to examine and modify message content and meta-information. Filtering policies implemented by Milter-conformant filters may then be centrally configured and composed in an end-user's MTA configuration file. <P> Possible uses for filters include spam rejection, virus filtering, and content control. In general, Milter seeks to address site-wide filtering concerns in a scalable way. Individual users' mail filtering needs (e.g. sorting messages by subject) are left to client-level programs such as <A href="http://www.procmail.org">Procmail</A>. <P> This document is a technical introduction intended for those interested in developing Milter filters. It includes: <UL> <LI>A description of Milter's design goals. <LI>An explanation of Milter application architecture, including interactions between the support library and user code, and between filters and the MTA. <LI>A specification of the C application programming interface. <LI>An example of a simple Milter filter. </UL> <H2>Contents</H2> <UL> <LI><A href="design.html">Architecture</A> <UL> <LI>Design Goals <LI>Implementing Filtering Policies <LI>MTA - Filter communication </UL> <LI><A href="overview.html">Technical Overview</A> <UL> <LI>Initialization <LI>Control flow <LI>Multithreading <LI>Resource Management <LI>Signal Handling </UL> <LI><A href="api.html">API Documentation</A> <UL> <LI>Library Control Functions <LI>Data Access Functions <LI>Message Modification Functions <LI>Callbacks </UL> <LI><A href="installation.html">Installation and Configuration</A> <UL> <LI>Compiling and Installing Your Filter <LI>Configuring Sendmail </UL> <LI><A href="sample.html">A Sample Filter</A> <!-- <LI><A href="other.html">Other Sources of Information</A> --> </UL> <HR size="1"> <FONT size="-1"> Copyright (c) 2000, 2001, 2003 Proofpoint, Inc. and its suppliers. All rights reserved. <BR> By using this file, you agree to the terms and conditions set forth in the LICENSE. </FONT> </BODY> </HTML> |