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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head>
  <meta http-equiv="content-type" content=
  "text/html; charset=utf-8" />
  <meta name="MSSmartTagsPreventParsing" content="TRUE" />
  <meta name="author" content="Mr. Sam"/>

  <title>The esmtp module</title>
  <!-- Copyright 2000-2004 Double Precision, Inc.  See COPYING for -->
  <!-- distribution information. -->
  <link rel="icon" href="icon.gif" type="image/gif" />
</head>

<body>
  <h2>The <code>esmtp</code> module</h2>- support for delivering
  and accepting mail via smtp/emstp over TCP/IP.

  <h3>Configuration
  files</h3><code>esmtpacceptmailfor,esmtpacceptmailfor.dat</code>
  - lists domains whose mail we accept.

  <p><code>esmtpgreeting</code> - what smtpd announces as its
  greeting.</p>

  <p><code>esmtphelo</code> - what to announce in my HELO command.
  Defaults to me.</p>

  <p><code>esmtppercentrelay.dat</code> - a GDBM database file. If
  address <code>&lt;user%foo@bar&gt;</code> is given, foo must be
  in percenthack as the key. Which is then rewritten by smtpd as
  <code>&lt;user@val&gt;</code>, where val is the value of that key
  in the GDBM file, which can be created by makegdbm.</p>

  <p><code>esmtproutes</code> - If the host being delivered to is
  found in this file, the value will be used instead of looking up
  MX or A records. The value is a space/tab separated list of IP
  addresses or hostnames.</p>

  <p><code>esmtptimeout</code> - general STMP timeout, in seconds.
  Both smtpd, and the output module will stop after waiting the
  specific amount for a response from the remote server.</p>

  <h2>Shared library</h2><code>rewritedel</code> - if domain is of
  the form foo@bar, accept delivery for host bar, user foo@bar.

  <p>Rewrite functions:</p>

  <p><code>esmtp</code> - compile-time options may be used to
  specify various kinds of behavior when envelope recipient is
  being rewritten by submit, including: check for mailbox validity
  - this involves simply locating any loaded rewritedel function,
  and failing otherwise (!); or forking and running an external
  filter!</p>

  <h2>Input module</h2>

  <p>courieresmtpd is typically invoked by couriertcpd to handle
  incoming connections. courieresmtpd is a full-fledged ESMTP
  server. courieresmtpd reads ESMTP commands and runs submit to
  process incoming messages.</p>

  <p>courieresmtpd reads BOFHNOEXPN and BOFHNOVRFY environment
  variables to disable the EXPN and VRFY commands.</p>

  <h2>Output module</h2>

  <p>The output module reads esmtproutes to check for any hardcoded
  smarthosts.</p>
</body>
</html>