<?xml version="1.0"?>

<!--
  Copyright (C) 2006, 2007 Anton Yuzhaninov
  Copyright (C) Nginx, Inc.
  -->

<!DOCTYPE module SYSTEM "../../../../dtd/module.dtd">

<module name="Module ngx_mail_proxy_module"
        link="/en/docs/mail/ngx_mail_proxy_module.html"
        lang="en"
        rev="5">

<section id="directives" name="Directives">

<!--
<directive name="proxy">
<syntax><literal>on</literal> | <literal>off</literal></syntax>
<default>off</default>
<context>mail</context>
<context>server</context>

<para>
Not tested anywhere in the current version.
</para>

</directive>
-->


<directive name="proxy_buffer">
<syntax><value>size</value></syntax>
<default>4k|8k</default>
<context>mail</context>
<context>server</context>

<para>
Sets the size of the buffer used for proxying.
By default, the buffer size is equal to one memory page.
Depending on a platform, it is either 4K or 8K.
</para>

</directive>


<directive name="proxy_pass_error_message">
<syntax><literal>on</literal> | <literal>off</literal></syntax>
<default>off</default>
<context>mail</context>
<context>server</context>

<para>
Indicates whether to pass the error message obtained during
the authentication on the backend to the client.
</para>

<para>
Usually, if the authentication in nginx is a success,
the backend cannot return an error.
If it nevertheless returns an error,
it means some internal error has occurred.
In such case the backend message can contain information
that should not be shown to the client.
However, responding with an error for the correct password
is a normal behavior for some POP3 servers.
For example, CommuniGatePro informs a user about
<link url="http://www.stalker.com/CommuniGatePro/Alerts.html#Quota">mailbox
overflow</link> or other events by periodically outputting the
<link url="http://www.stalker.com/CommuniGatePro/POP.html#Alerts">authentication
error</link>.
The directive should be enabled in this case.
</para>

</directive>


<directive name="proxy_protocol">
<syntax><literal>on</literal> | <literal>off</literal></syntax>
<default>off</default>
<context>mail</context>
<context>server</context>
<appeared-in>1.19.8</appeared-in>

<para>
Enables the
<link url="http://www.haproxy.org/download/1.5/doc/proxy-protocol.txt">PROXY
protocol</link> for connections to a backend.
</para>

</directive>


<directive name="proxy_smtp_auth">
<syntax><literal>on</literal> | <literal>off</literal></syntax>
<default>off</default>
<context>mail</context>
<context>server</context>
<appeared-in>1.19.4</appeared-in>

<para>
Enables or disables user authentication on the SMTP backend
using the <literal>AUTH</literal> command.
</para>

<para>
If <link id="xclient">XCLIENT</link> is also enabled,
then the <literal>XCLIENT</literal> command will not send
the <literal>LOGIN</literal> parameter.
</para>

</directive>


<directive name="proxy_timeout">
<syntax><value>timeout</value></syntax>
<default>24h</default>
<context>mail</context>
<context>server</context>

<para>
Sets the <value>timeout</value> between two successive
read or write operations on client or proxied server connections.
If no data is transmitted within this time, the connection is closed.
</para>

</directive>


<directive name="xclient">
<syntax><literal>on</literal> | <literal>off</literal></syntax>
<default>on</default>
<context>mail</context>
<context>server</context>

<para>
Enables or disables the passing of the
<link url="http://www.postfix.org/XCLIENT_README.html">XCLIENT</link>
command with client parameters when connecting to the SMTP backend.
</para>

<para>
With <literal>XCLIENT</literal>, the MTA is able to write client information
to the log and apply various limitations based on this data.
</para>

<para>
If <literal>XCLIENT</literal> is enabled
then nginx passes the following commands when connecting to the backend:
<list type="bullet">
<listitem>
<literal>EHLO</literal> with the
<link doc="ngx_mail_core_module.xml" id="server_name">server name</link>
</listitem>

<listitem>
<literal>
XCLIENT
</literal>
</listitem>

<listitem>
<literal>EHLO</literal> or <literal>HELO</literal>,
as passed by the client
</listitem>
</list>
</para>

<para>
If the name
<link doc="ngx_mail_core_module.xml" id="resolver">found</link>
by the client IP address points to the same address,
it is passed in the <literal>NAME</literal> parameter
of the <literal>XCLIENT</literal> command.
If the name could not be found, points to a different address,
or <link doc="ngx_mail_core_module.xml" id="resolver"/> is not specified,
the <literal>[UNAVAILABLE]</literal> is passed
in the <literal>NAME</literal> parameter.
If an error has occurred in the process of resolving,
the <literal>[TEMPUNAVAIL]</literal> value is used.
</para>

<para>
If <literal>XCLIENT</literal> is disabled
then nginx passes the <literal>EHLO</literal> command with the
<link doc="ngx_mail_core_module.xml" id="server_name">server name</link>
when connecting to the backend if the client has passed
<literal>EHLO</literal>,
or <literal>HELO</literal> with the server name, otherwise.
</para>

</directive>

</section>

</module>