dist/proto/INSTALL.html

<!doctype html public "-//W3C//DTD HTML 4.01 Transitional//EN"
        "https://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<title>Postfix Installation From Source Code </title>

<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link rel='stylesheet' type='text/css' href='postfix-doc.css'>

</head>

<body>

<h1><img src="postfix-logo.jpg" width="203" height="98" ALT="">Postfix
Installation From Source Code </h1>

<hr>

<h2> <a name="1">1 - Purpose of this document</a> </h2>

<p> If you are using a pre-compiled version of Postfix, you should
start with BASIC_CONFIGURATION_README and the general documentation
referenced by it.  INSTALL is only a bootstrap document to get
Postfix up and running from scratch with the minimal number of
steps; it should not be considered part of the general documentation.
</p>

<p> This document describes how to build, install and configure a
Postfix system so that it can do one of the following: </p>

<ul>

<li> Send mail only, without changing an existing Sendmail
installation.

<li> Send and receive mail via a virtual host interface, still
without any change to an existing Sendmail installation.

<li> Run Postfix instead of Sendmail.

</ul>

<p> Topics covered in this document: </p>

<ol>

<li> <a href="#1">Purpose of this document</a>

<li> <a href="#2">Typographical conventions</a>

<li> <a href="#3">Documentation</a>

<li> <a href="#4">Building on a supported system</a>

<li> <a href="#5">Porting Postfix to an unsupported system</a>

<li> <a href="#install">Installing the software after successful
compilation </a>

<li> <a href="#send_only">Configuring Postfix to send mail
only </a>

<li> <a href="#send_receive">Configuring Postfix to send and
receive mail via virtual interface </a>

<li> <a href="#replace">Running Postfix instead of Sendmail</a>

<li> <a href="#mandatory">Mandatory configuration file edits</a>

<li> <a href="#hamlet">To chroot or not to chroot</a>

<li> <a href="#care">Care and feeding of the Postfix system</a>

</ol>

<h2> <a name="2">2 - Typographical conventions</a> </h2>

<p> In the instructions below, a command written as </p>

<blockquote>
<pre>
# command
</pre>
</blockquote>

<p> should be executed as the superuser. </p>

<p> A command written as </p>

<blockquote>
<pre>
$ command
</pre>
</blockquote>

<p> should be executed as an unprivileged user.  </p>

<h2> <a name="3">3 - Documentation</a> </h2>

<p> Documentation is available as README files (start with the file
README_FILES/AAAREADME), as HTML web pages (point your browser to
"html/index.html") and as UNIX-style manual pages. </p>

<p> You should view the README files with a pager such as more(1)
or less(1), because the files use backspace characters in order to
produce <b>bold</b> font. To print a README file without backspace
characters, use the col(1) command.  For example: </p>

<blockquote>
<pre>
$ col -bx &lt;file | lpr
</pre>
</blockquote>

<p> In order to view the manual pages before installing Postfix,
point your MANPATH environment variable to the "man" subdirectory;
be sure to use an absolute path.  </p>

<blockquote>
<pre>
$ export MANPATH; MANPATH="`pwd`/man:$MANPATH"
$ setenv MANPATH "`pwd`/man:$MANPATH"
</pre>
</blockquote>

<p> Of particular interest is the postconf(5) manual page that lists
all the 900+ configuration parameters. The hyperlinks in the HTML
version (html/postconf.5.html) make the text easy to navigate. </p>

<p> All Postfix source files have their own built-in manual page.
Tools to extract those embedded manual pages are available in the
mantools directory. </p>

<h2> <a name="4">4 - Building on a supported system</a> </h2>

<p> Postfix development happens on FreeBSD and Linux, with occasional
tests on Solaris. Support for other systems relies on feedback from
their users, and may not always be up-to-date. </p>

<p> OpenBSD is partially supported. The libc resolver does not
implement the documented "internal resolver options which are [...]
set by changing fields in the _res structure" (documented in the
OpenBSD 5.6 resolver(3) manpage). This results in too many DNS
queries, and false positives for queries that should fail. </p>

<!--

<p> At some point in time, a version of Postfix was supported on: </p>

<blockquote>
<p>
AIX 3.2.5, 4.1.x, 4.2.0, 4.3.x, 5.2 <br>
BSD/OS 2.x, 3.x, 4.x <br>
FreeBSD 2.x .. 9.x <br>
HP-UX  9.x, 10.x, 11.x <br>
IRIX 5.x, 6.x <br>
Linux Debian 1.3.1 and later <br>
Linux RedHat 3.x (January 2004) and later <br>
Linux Slackware 3.x and later <br>
Linux SuSE 5.x and later <br>
Linux Ubuntu 4.10 and later<br>
Mac OS X <br>
NEXTSTEP 3.x <br>
NetBSD 1.x and later <br>
OPENSTEP 4.x <br>
OSF1.V3 - OSF1.V5 (Digital UNIX) <br>
Reliant UNIX 5.x <br>
SunOS 4.1.4 (March 2007) <br>
SunOS 5.4 - 5.10 (Solaris 2.4..10) <br>
Ultrix 4.x (well, that was long ago) <br>
</p>
</blockquote>

<p> or something closely resemblant. </p>

-->

<p> Overview of topics: </p>

<ul>

<li><a href="#build_first">4.1 - Getting started</a>

<li><a href="#build_cc">4.2 - What compiler to use</a>

<li><a href="#build_pie">4.3 - Building with Postfix position-independent
executables (Postfix &ge; 3.0)</a>

<li><a href="#build_dll">4.4 - Building with Postfix dynamically-linked
libraries and database plugins (Postfix &ge; 3.0)</a>

<li><a href="#build_opt">4.5 - Building with optional features</a>

<li><a href="#build_over">4.6 - Overriding built-in parameter default
settings</a>

<li><a href="#build_other">4.7 - Overriding other compile-time
features</a>

<li><a href="#build_proc">4.8 - Support for thousands of processes</a>

<li><a href="#build_final">4.9 - Compiling Postfix, at last</a>

</ul>


<h3><a name="build_first">4.1 - Getting started</a> </h3>

<p> On Solaris, the "make" command and other development utilities
are in /usr/ccs/bin, so you MUST have /usr/ccs/bin in your command
search path. If these files do not exist, you need to install the
development packages first. </p>

<p> If you need to build Postfix for multiple architectures from a
single source-code tree, use the "lndir" command to build a shadow
tree with symbolic links to the source files. </p>

<p> If at any time in the build process you get messages like: "make:
don't know how to ..." you should be able to recover by running
the following command from the Postfix top-level directory: </p>

<blockquote>
<pre>
$ make -f Makefile.init makefiles
</pre>
</blockquote>

<p> If you copied the Postfix source code after building it on another
machine, it is a good idea to cd into the top-level directory and
first do this:</p>

<blockquote>
<pre>
$ make tidy
</pre>
</blockquote>

<p> This will get rid of any system dependencies left over from
compiling the software elsewhere. </p>

<h3><a name="build_cc">4.2 - What compiler to use</a></h3>

<p> To build with GCC, or with the native compiler if people told me
that is better for your system, just cd into the top-level Postfix
directory of the source tree and type: </p>

<blockquote>
<pre>
$ make
</pre>
</blockquote>

<p> To build with a non-default compiler, you need to specify the name
of the compiler. Here are a few examples: </p>

<blockquote>
<pre>
$ make makefiles CC=/opt/SUNWspro/bin/cc        (Solaris)
$ make

$ make makefiles CC="/opt/ansic/bin/cc -Ae"     (HP-UX)
$ make

$ make makefiles CC="purify cc"
$ make
</pre>
</blockquote>

<p> and so on. In some cases, optimization will be turned off
automatically. </p>

<h3><a name="build_pie">4.3 - Building with Postfix position-independent
executables (Postfix &ge; 3.0)</a> </h3>

<p> On some systems Postfix can be built with Position-Independent
Executables. PIE is used by the ASLR exploit mitigation technique
(ASLR = Address-Space Layout Randomization): </p>

<blockquote>
<pre>
$ make makefiles pie=yes ...other arguments...
</pre>
</blockquote>

<p> (Specify "make makefiles pie=no" to explicitly disable Postfix
position-independent executable support). </p>

<p> Postfix PIE support appears to work on Fedora Core 20, Ubuntu
14.04, FreeBSD 9 and 10, and NetBSD 6 (all with the default system
compilers). </p>

<p> Whether the "pie=yes" above has any effect depends on the
compiler.  Some compilers always produce PIE executables, and some
may even complain that the Postfix build option is redundant. </p>

<h3><a name="build_dll">4.4 - Building with Postfix dynamically-linked
libraries and database plugins (Postfix &ge; 3.0)</a> </h3>

<p> Postfix dynamically-linked library and database plugin support
exists for recent versions of Linux, FreeBSD and MacOS X.
Dynamically-linked library builds may become the default at some
point in the future. </p>

<p> Overview of topics: </p>

<ul>

<li><a href="#shared_enable">4.4.1 Turning on Postfix dynamically-linked
library support</a>

<li><a href="#dynamicmaps_enable">4.4.2 Turning on Postfix database-plugin
support</a>

<li><a href="#shared_custom">4.4.3 Customizing Postfix dynamically-linked
libraries and database plugins</a>

<li><a href="#shared_tips">4.4.4 Tips for distribution maintainers</a>

</ul>

<p> Note: directories with Postfix dynamically-linked  libraries
or database plugins should contain only postfix-related files.
Postfix dynamically-linked libraries and database plugins should
not be installed in a "public" system directory such as /usr/lib
or /usr/local/lib.  Linking Postfix dynamically-linked library or
database-plugin files into non-Postfix programs is not supported.
Postfix dynamically-linked libraries and database plugins implement
a Postfix-internal API that changes without maintaining compatibility.
</p>

<h4><a name="shared_enable"> 4.4.1 Turning on Postfix dynamically-linked
library support </a></h4>

<p> Postfix can be built with Postfix dynamically-linked libraries
(files typically named <tt>libpostfix-*.so</tt>). Postfix
dynamically-linked libraries add minor run-time overhead and result
in significantly-smaller Postfix executable files. </p>

<p> Specify "shared=yes" on the "make makefiles" command line to
build Postfix with dynamically-linked library support. </p>

<blockquote>
<pre>
$ make makefiles shared=yes ...other arguments...
$ make
</pre>
</blockquote>

<p> (Specify "make makefiles shared=no" to explicitly disable Postfix
dynamically-linked library support). </p>

<p> This installs dynamically-linked libraries in $shlib_directory,
typically /usr/lib/postfix or /usr/local/lib/postfix, with file
names libpostfix-<i>name</i>.so, where the <i>name</i> is a source-code
directory name such as "util" or "global".  </p>

<p> See section 4.4.3 "<a href="#shared_custom">Customizing Postfix
dynamically-linked libraries and database plugins</a>" below for
how to customize the Postfix dynamically-linked library location,
including support to upgrade a running mail system safely.  </p>

<h4><a name="dynamicmaps_enable"> 4.4.2 Turning on Postfix
database-plugin support </a></h4>

<p> Additionally, Postfix can be built to support dynamic loading
of Postfix database clients (database plugins) with the Debian-style
dynamicmaps feature. Postfix 3.0 supports dynamic loading of cdb:,
ldap:, lmdb:, mysql:, pcre:, pgsql:, sdbm:, and sqlite: database
clients.  Dynamic loading is useful when you distribute or install
pre-compiled Postfix packages. </p>

<p> Specify "dynamicmaps=yes" on the "make makefiles" command line
to build Postfix with support to dynamically load Postfix database
clients with the Debian-style dynamicmaps feature.
</p>

<blockquote>
<pre>
$ make makefiles dynamicmaps=yes ...other arguments...
$ make
</pre>
</blockquote>

<p> (Specify "make makefiles dynamicmaps=no" to explicitly disable
Postfix database-plugin support). </p>

<p> This implicitly enables dynamically-linked library support,
installs the configuration file dynamicmaps.cf in $meta_directory
(usually, /etc/postfix or /usr/local/etc/postfix), and installs
database plugins in $shlib_directory (see above).  Database plugins
are named postfix-<i>type</i>.so where the <i>type</i> is a database
type such as "cdb" or "ldap". </p>

<blockquote>

<p> NOTE: The Postfix 3.0 build procedure expects that you specify
database library dependencies with variables named AUXLIBS_CDB,
AUXLIBS_LDAP, etc.  With Postfix 3.0 and later, the old AUXLIBS
variable still supports building a statically-loaded database client,
but only the new AUXLIBS_CDB etc. variables support building a
dynamically-loaded or statically-loaded CDB etc. database client.
See CDB_README, LDAP_README, etc. for details.  </p>

<p> Failure to follow this advice will defeat the purpose of dynamic
database client loading. Every Postfix executable file will have
database library dependencies. And that was exactly what dynamic
database client loading was meant to avoid. </p>

</blockquote>

<p> See the next section for how to customize the location and
version of Postfix database plugins and the location of the file
dynamicmaps.cf.  </p>

<h4><a name="shared_custom"> 4.4.3 Customizing Postfix dynamically-linked
libraries and database plugins </a></h4>

<h5> Customizing build-time and run-time options for Postfix
dynamically-linked libraries and database plugins </h5>

<p> The build-time environment variables SHLIB_CFLAGS, SHLIB_RPATH,
and SHLIB_SUFFIX provide control over how Postfix libraries and
plugins are compiled, linked, and named.

<blockquote>
<pre>
$ make makefiles SHLIB_CFLAGS=flags SHLIB_RPATH=rpath SHLIB_SUFFIX=suffix ...other arguments...
$ make
</pre>
</blockquote>

<p> See section 4.7 "<a href="#build_other">Overriding other
compile-time features</a>" below for details. </p>

<h5> Customizing the location of Postfix dynamically-linked libraries
and database plugins </h5>

<p> As a reminder, the directories with Postfix dynamically-linked
libraries or database plugins should contain only Postfix-related
files.  Linking these files into other programs is not supported.
</p>

<p> To override the default location of Postfix dynamically-linked
libraries and database plugins specify, for example: </p>

<blockquote>
<pre>
$ make makefiles shared=yes shlib_directory=/usr/local/lib/postfix ...
</pre>
</blockquote>

<p> If you intend to upgrade Postfix without stopping the mail
system, then you should append the Postfix release version to the
shlib_directory pathname, to eliminate the possibility that programs
will link with dynamically-linked libraries or database plugins
from the wrong Postfix version.  For example: </p>

<blockquote>
<pre>
$ make makefiles shared=yes \
    shlib_directory=/usr/local/lib/postfix/MAIL_VERSION ...
</pre>
</blockquote>

<p> The command "make makefiles name=value..." will replace the
string MAIL_VERSION at the end of a configuration parameter value
with the Postfix release version. Do not try to specify something
like $mail_version on this command line. This produces inconsistent
results with different versions of the make(1) command.  </p>

<p> You can change the shlib_directory setting after Postfix is
built, with "make install" or "make upgrade". However, you may have
to run ldconfig if you change shlib_directory after Postfix is built
(the symptom is that Postfix programs fail because the run-time
linker cannot find the files libpostfix-*.so).  No ldconfig command
is needed if you keep the files libpostfix-*.so in the compiled-in
default $shlib_directory location. </p>

<blockquote>
<pre>
# make upgrade shlib_directory=/usr/local/lib/postfix ...
# make install shlib_directory=/usr/local/lib/postfix ...
</pre>
</blockquote>

<p> To append the Postfix release version to the pathname if you
intend to upgrade Postfix without stopping the mail system:  </p>

<blockquote>
<pre>
# make upgrade shlib_directory=/usr/local/lib/postfix/MAIL_VERSION ...
# make install shlib_directory=/usr/local/lib/postfix/MAIL_VERSION ...
</pre>
</blockquote>

<p> See also the comments above for appending MAIL_VERSION with
the "make makefiles" command. </p>

<h5> Customizing the location of dynamicmaps.cf and other files
</h5>

<p> The meta_directory parameter has the same default setting as
the config_directory parameter, typically /etc/postfix or
/usr/local/etc/postfix. </p>

<p> You can override the default meta_directory location at compile
time or after Postfix is built. To override the default location
at compile time specify, for example: </p>

<blockquote>
<pre>
% make makefiles meta_directory=/usr/libexec/postfix ...
</pre>
</blockquote>

<p> Here is a tip if you want to make a pathname dependent on the
Postfix release version: the command "make makefiles name=value..."
will replace the string MAIL_VERSION at the end of a configuration
parameter value with the Postfix release version. Do not try to
specify something like $mail_version on this command line. This
produces inconsistent results with different versions of the make(1)
command.  </p>

<p> You can override the meta_directory setting after Postfix is
built, with "make install" or "make upgrade". </p>

<blockquote>
<pre>
# make upgrade meta_directory=/usr/libexec/postfix ...
# make install meta_directory=/usr/libexec/postfix ...
</pre>
</blockquote>

<p> As with the command "make makefiles", the command "make
install/upgrade name=value..." will replace the string MAIL_VERSION
at the end of a configuration parameter value with the Postfix
release version.  Do not try to specify something like $mail_version
on this command line. This produces inconsistent results with
different versions of the make(1) command.  </p>

<h4><a name="shared_tips"> 4.4.4 Tips for distribution maintainers
</a></h4>

<ul>

<li> <p> The shlib_directory parameter setting also provides the
default directory for database plugin files with a relative pathname
in the file dynamicmaps.cf. </p>

<li> <p> The meta_directory parameter specifies the location of the
files dynamicmaps.cf, postfix-files, and some multi-instance template
files. The meta_directory parameter has the same default value as
the config_directory parameter (typically, /etc/postfix or
/usr/local/etc/postfix). For backwards compatibility with Postfix
2.6 .. 2.11, specify "meta_directory = $daemon_directory" in main.cf
before installing or upgrading Postfix, or specify "meta_directory
= /path/name" on the "make makefiles", "make install" or "make
upgrade" command line.  </p>

<li> <p> The configuration file dynamicmaps.cf will automatically
include files under the directory dynamicmaps.cf.d, just like the
configuration file postfix-files will automatically include files
under the directory postfix-files.d.  Thanks to this, you can install
or deinstall a database plugin package without having to edit
postfix-files or dynamicmaps.cf. Instead, you give that plugin its
own configuration files under dynamicmaps.cf.d and postfix-files.d, and
you add or remove those configuration files along with the database
plugin dynamically-linked object.  </p>

<li> <p> Each configuration file under the directory dynamicmaps.cf.d
must have the same format as the configuration file dynamicmaps.cf.
There is no requirement that these configuration file *names* have a
specific format.  </p>

<li> <p> Each configuration file under the directory postfix-files.d
must have the same format as the configuration file postfix-files.
There is no requirement that these configuration file *names* have a
specific format.  </p>

</ul>

<h3><a name="build_opt">4.5 - Building with optional features</a></h3>

By default, Postfix builds as a mail system with relatively few
bells and whistles. Support for third-party databases etc.
must be configured when Postfix is compiled.  The following documents
describe how to build Postfix with support for optional features:

<blockquote>
<table border="1">

<tr> <th>Optional feature </th> <th>Document </th> <th>Availability</th>
</tr>

<tr> <td> Berkeley DB database</td> <td>DB_README</td> <td> Postfix
1.0 </td> </tr>

<tr> <td> CDB database</td> <td>CDB_README</td> <td> Postfix
2.2 </td> </tr>

<tr> <td> LMDB database</td> <td>LMDB_README</td> <td> Postfix
2.11 </td> </tr>

<tr> <td> LDAP database</td> <td>LDAP_README</td> <td> Postfix
1.0 </td> </tr>

<tr> <td> MongoDB database</td> <td>MONGODB_README</td> <td> Postfix
3.9 </td> </tr>

<tr> <td> MySQL database</td> <td>MYSQL_README</td> <td> Postfix
1.0 </td> </tr>

<tr> <td> Perl compatible regular expression</td> <td>PCRE_README</td>
<td> Postfix 1.0 </td> </tr>

<tr> <td> PostgreSQL database</td> <td>PGSQL_README</td> <td>
Postfix 2.0 </td> </tr>

<tr> <td> SASL authentication </td> <td>SASL_README</td> <td>
Postfix 1.0 </td> </tr>

<tr> <td> SQLite database</td> <td>SQLITE_README</td> <td> Postfix
2.8 </td> </tr>

<tr> <td> STARTTLS session encryption </td> <td>TLS_README</td> <td>
Postfix 2.2 </td> </tr>

</table>

</blockquote>

<p> Note: IP version 6 support is compiled into Postfix on operating
systems that have IPv6 support. See the IPV6_README file for details.
</p>

<h3><a name="build_over">4.6 - Overriding built-in parameter default
settings</a></h3>

<h4>4.6.1 - Postfix 3.0 and later </h4>

<p> All Postfix configuration parameters can be changed by editing
a Postfix configuration file, except for one: the parameter that
specifies the location of Postfix configuration files. In order to
build Postfix with a configuration directory other than /etc/postfix,
use: </p>

<blockquote>
<pre>
$ make makefiles config_directory=/some/where ...other arguments...
$ make
</pre>
</blockquote>

<p> The command "make makefiles name=value ..." will replace the
string MAIL_VERSION at the end of a configuration parameter value
with the Postfix release version. Do not try to specify something
like $mail_version on this command line. This produces inconsistent
results with different versions of the make(1) command.  </p>

<p> Parameters whose defaults can be specified in this way are
listed below. See the postconf(5) manpage for a description
(command: "<tt>nroff -man man/man5/postconf.5 | less</tt>").  </p>

<blockquote>

<table border="1">

<tr> <th>parameter name</th>  <th>typical default</th> </tr>

<tr> <td>command_directory</td> <td>/usr/sbin</td> </tr>

<tr> <td>config_directory</td> <td>/etc/postfix</td> </tr>

<tr> <td>default_database_type</td> <td>lmdb, cdb, or hash</td> </tr>

<tr> <td>default_cache_db_type</td> <td>lmdb or btree</td> </tr>

<tr> <td>daemon_directory</td> <td>/usr/libexec/postfix</td> </tr>

<tr> <td>data_directory</td> <td>/var/lib/postfix</td> </tr>

<tr> <td>html_directory</td> <td>no</td> </tr>

<tr> <td>mail_spool_directory</td> <td>/var/mail</td> </tr>

<tr> <td>mailq_path</td> <td>/usr/bin/mailq</td> </tr>

<tr> <td>manpage_directory</td> <td>/usr/local/man</td> </tr>

<tr> <td>meta_directory</td> <td>/etc/postfix</td> </tr>

<tr> <td>newaliases_path</td> <td>/usr/bin/newaliases</td> </tr>

<tr> <td>openssl_path</td> <td>openssl</td> </tr>

<tr> <td>queue_directory</td> <td>/var/spool/postfix</td> </tr>

<tr> <td>readme_directory</td> <td>no</td> </tr>

<tr> <td>sendmail_path</td> <td>/usr/sbin/sendmail</td> </tr>

<tr> <td>shlib_directory</td> <td>/usr/lib/postfix</td> </tr>

</table>

</blockquote>

<h4>4.6.2 - All Postfix versions </h4>

<p> All Postfix configuration parameters can be changed by editing
a Postfix configuration file, except for one: the parameter that
specifies the location of Postfix configuration files. In order to
build Postfix with a configuration directory other than /etc/postfix,
use: </p>

<blockquote>
<pre>
$ make makefiles CCARGS="-DDEF_CONFIG_DIR=\\\"/some/where\\\""
$ make
</pre>
</blockquote>

<p> IMPORTANT: Be sure to get the quotes right. These details matter
a lot. </p>

<p> Parameters whose defaults can be specified in this way are
listed below. See the postconf(5) manpage for a description
(command: "<tt>nroff -man man/man5/postconf.5 | less</tt>").  </p>

<blockquote>

<table border="1">

<tr><th> Macro name </th> <th>default value for</th>  <th>typical
default</th> </tr>

<tr> <td>DEF_COMMAND_DIR</td> <td>command_directory</td>
<td>/usr/sbin</td> </tr>

<tr> <td>DEF_CONFIG_DIR</td> <td>config_directory</td>
<td>/etc/postfix</td> </tr>

<tr> <td>DEF_DB_TYPE</td> <td>default_database_type</td>
<td>lmdb, cdb, or hash</td> </tr>

<tr> <td>DEF_CACHE_DB_TYPE</td> <td>default_cache_db_type</td>
<td>lmdb or btree</td> </tr>

<tr> <td>DEF_DAEMON_DIR</td> <td>daemon_directory</td>
<td>/usr/libexec/postfix</td> </tr>

<tr> <td>DEF_DATA_DIR</td> <td>data_directory</td>
<td>/var/db/postfix</td> </tr>

<tr> <td>DEF_MAILQ_PATH</td> <td>mailq_path</td> <td>/usr/bin/mailq</td>
</tr>

<tr> <td>DEF_HTML_DIR</td> <td>html_directory</td>
<td>no</td> </tr>

<tr> <td>DEF_MANPAGE_DIR</td> <td>manpage_directory</td>
<td>/usr/local/man</td> </tr>

<tr> <td>DEF_NEWALIAS_PATH</td> <td>newaliases_path</td>
<td>/usr/bin/newaliases</td> </tr>

<tr> <td>DEF_QUEUE_DIR</td> <td>queue_directory</td>
<td>/var/spool/postfix</td> </tr>

<tr> <td>DEF_README_DIR</td> <td>readme_directory</td>
<td>no</td> </tr>

<tr> <td>DEF_SENDMAIL_PATH</td> <td>sendmail_path</td>
<td>/usr/sbin/sendmail</td> </tr>

<tr> <td>DEF_SHLIB_DIR</td> <td>shlib_directory</td>
<td>/usr/lib/postfix</td> </tr>

</table>

</blockquote>

<p> Note: the data_directory parameter (for caches and pseudo-random
numbers) was introduced with Postfix version 2.5; shlib_directory
(for shared-library objects and database plugins) with Postfix
version 3.0. </p>

<h3><a name="build_other">4.7 - Overriding other compile-time
features</a></h3>

<p> The general method to override Postfix compile-time features
is as follows: </p>

<blockquote>
<pre>
$ make makefiles name=value name=value...
$ make
</pre>
</blockquote>

<p> The following is an extensive list of names and values. </p>

<table border="1">

<tr> <th colspan="2"> Name/Value </th> <th> Description </th> </tr>

<tr> <td colspan="2"> AUXLIBS="object_library..."</td> <td> Specifies
one or more non-default object libraries. Postfix 3.0 and later
specify some of their database library dependencies with AUXLIBS_CDB,
AUXLIBS_LDAP, AUXLIBS_LMDB, AUXLIBS_MYSQL, AUXLIBS_PCRE, AUXLIBS_PGSQL,
AUXLIBS_SDBM, and AUXLIBS_SQLITE, respectively. </td> </tr>

<tr> <td colspan="2"> CC=compiler_command</td> <td> Specifies a
non-default compiler. On many systems, the default is <tt>gcc</tt>.
</td> </tr>

<tr> <td colspan="2"> CCARGS="compiler_arguments..."</td> <td>
Specifies non-default compiler arguments, for example, a non-default
<tt>include</tt> directory.  The following directives turn
off Postfix features at compile time:</td> </tr>

<tr> <td> </td> <td> -DNO_DB </td> <td> Do not build with Berkeley
DB support. By default, Berkeley DB support is compiled in on
platforms that have historically supported this feature. If you override
this, then you probably should also override default_database_type
or DEF_DB_TYPE as described in section 4.6. </td> </tr>

<tr> <td> </td> <td> -DNO_DNSSEC </td> <td> Do not build with DNSSEC
support, even if the resolver library appears to support it. </td>
</tr>

<tr> <td> </td> <td> -DNO_DEVPOLL </td> <td> Do not build with
Solaris <tt>/dev/poll</tt> support. By default, <tt>/dev/poll</tt>
support is compiled in on Solaris versions that are known to support
this feature.  </td> </tr>

<tr> <td> </td> <td> -DNO_EPOLL </td> <td> Do not build with Linux
EPOLL support.  By default, EPOLL support is compiled in on platforms
that are known to support this feature. </td> </tr>

<tr> <td> </td> <td> -DNO_EAI </td> <td> Do not build with EAI
(SMTPUTF8) support. By default, EAI support is compiled in when
the "icuuc" library and header files are found.  </td> </tr>

<tr> <td> </td> <td> -DNO_INLINE </td> <td> Do not require support
for C99 "inline" functions. Instead, implement argument typechecks
for non-printf/scanf-like functions with ternary operators and
unreachable code. </td> </tr>

<tr> <td> </td> <td> -DNO_IPV6 </td> <td> Do not build with IPv6
support. By default, IPv6 support is compiled in on platforms that
are known to have IPv6 support. Note: this directive is for debugging
and testing only. It is not guaranteed to work on all platforms.
If you don't want IPv6 support, set "inet_protocols = ipv4" in
main.cf.
</td> </tr>

<tr> <td> </td> <td> -DNO_KQUEUE </td> <td> Do not build with FreeBSD
/ NetBSD / OpenBSD / MacOSX KQUEUE support. By default, KQUEUE
support is compiled in on platforms that are known to support it.
</td> </tr>

<tr> <td> </td> <td> -DNO_NIS </td> <td> Do not build with NIS or
NISPLUS support. NIS is not available on some recent Linux
distributions. </td> </tr>

<tr> <td> </td> <td> -DNO_NISPLUS </td> <td> Do not build with
NISPLUS support. NISPLUS is not available on some recent Solaris
distributions. </td> </tr>

<tr> <td> </td> <td> -DNO_PCRE </td> <td> Do not build with PCRE
support. By default, PCRE support is compiled in when the
<tt>pcre-config</tt> utility is installed. </td> </tr>

<tr> <td> </td> <td> -DNO_POSIX_GETPW_R </td> <td> Disable support
for POSIX <tt>getpwnam_r/getpwuid_r</tt>. By default Postfix uses
these where they are known to be available. </td> </tr>

<tr> <td> </td> <td> -DNO_RES_NCALLS </td> <td> Do not build with
the threadsafe resolver(5) API (res_ninit() etc.). </td> </tr>

<tr> <td> </td> <td> -DNO_SIGSETJMP </td> <td> Use
<tt>setjmp()/longjmp()</tt> instead of <tt>sigsetjmp()/siglongjmp()</tt>.
By default, Postfix uses <tt>sigsetjmp()/siglongjmp()</tt> when
they are known to be available. </td> </tr>

<tr> <td> </td> <td> -DNO_SNPRINTF </td> <td> Use <tt>sprintf()</tt>
instead of <tt>snprintf()</tt>.  By default, Postfix uses
<tt>snprintf()</tt> except on ancient systems. </td> </tr>

<tr> <td colspan="2"> DEBUG=debug_level </td> <td> Specifies a
non-default compiler debugging level. The default is "<tt>-g</tt>".
Specify DEBUG= to turn off debugging. </td> </tr>

<tr> <td colspan="2"> OPT=optimization_level </td> <td> Specifies
a non-default optimization level. The default is "<tt>-O</tt>".
Specify OPT= to turn off optimization. </td> </tr>

<tr> <td colspan="2"> POSTFIX_INSTALL_OPTS=-option... </td> <td>
Specifies options for the <tt>postfix-install</tt> command, separated
by whitespace. Currently, the only supported option is
"<tt>-keep-build-mtime</tt>". </td> </tr>

<tr> <td colspan="2"> SHLIB_CFLAGS=flags </td> <td> Specifies
non-default compiler options for building Postfix dynamically-linked
libraries and database plugins. The typical default is "-fPIC".
</td> </tr>

<tr> <td colspan="2"> SHLIB_RPATH=rpath </td> <td> Specifies
a non-default runpath for Postfix dynamically-linked libraries. The
typical default is "'-Wl,-rpath,${SHLIB_DIR}'". </td> </tr>

<tr> <td colspan="2"> SHLIB_SUFFIX=suffix </td> <td> Specifies
a non-default suffix for Postfix dynamically-linked libraries and
database plugins.  The typical default is "<tt>.so</tt>". </td>
</tr>

<tr> <td colspan="2"> WARN="warning_flags..." </td> <td> Specifies
non-default compiler warning options for use when "<tt>make</tt>"
is invoked in a source subdirectory only. </td>
</tr>

</table>

<h3><a name="build_proc">4.8 - Support for thousands of processes</a></h3>

<p> The number of connections that Postfix can manage simultaneously
is limited by the number of processes that it can run.  This number
in turn is limited by the number of files and sockets that a single
process can open. For example, the Postfix queue manager has a
separate connection to each delivery process, and the anvil(8)
server has one connection per smtpd(8) process. </p>

<p> Postfix version 2.4 and later have no built-in limits on the
number of open files or sockets, when compiled on systems that
support one of the following: </p>

<ul>

<li> BSD kqueue(2) (FreeBSD 4.1, NetBSD 2.0, OpenBSD 2.9),

<li> Solaris 8 /dev/poll,

<li> Linux 2.6 epoll(4).

</ul>


<p> With other Postfix versions or operating systems, the number
of file descriptors per process is limited by the value of the
FD_SETSIZE macro. If you expect to run more than 1000 mail delivery
processes, you may need to override the definition of the FD_SETSIZE
macro to make select() work correctly: </p>

<blockquote>
<pre>
$ make makefiles CCARGS=-DFD_SETSIZE=2048
</pre>
</blockquote>

<p> Warning: the above has no effect on some Linux versions.
Apparently, on these systems the FD_SETSIZE value can be changed
only by using undocumented interfaces. Currently, that means
including &lt;bits/types.h&gt; directly (which is not allowed) and
overriding the __FD_SETSIZE macro. Beware, undocumented interfaces
can change at any time and without warning. </p>

<p> But wait, there is more: none of this will work unless the
operating system is configured to handle thousands of connections.
See the TUNING_README guide for examples of how to increase the
number of open sockets or files. </p>

<h3><a name="build_final">4.9 - Compiling Postfix, at last</a></h3>

<p> If the command </p>

<blockquote>
<pre>
$ make
</pre>
</blockquote>

<p> is successful, then you can proceed to <a href="#install">install</a>
Postfix (section 6).

<p> If the command produces compiler error messages, it may be time
to search the web or to ask the postfix-users (a] postfix.org mailing
list, but be sure to search the mailing list archives first. Some
mailing list archives are linked from https://www.postfix.org/. </p>

<h2> <a name="5">5 - Porting Postfix to an unsupported system</a> </h2>

<p> Each system type that Postfix knows is identified by a unique
name. Examples:  SUNOS5, FREEBSD4, and so on.  When porting Postfix
to a new system, the first step is to choose a SYSTEMTYPE name for
the new system. You must use a name that includes at least the
major version of the operating system (such as SUNOS4 or LINUX2),
so that different releases of the same system can be supported
without confusion.  </p>

<p> Add a case statement to the "makedefs" shell script in the
source code top-level directory that recognizes the new system
reliably, and that emits the right system-specific information.
Be sure to make the code robust against user PATH settings; if the
system offers multiple UNIX flavors (e.g. BSD and SYSV) be sure to
build for the native flavor, instead of the emulated one. </p>

<p> Add an "#ifdef SYSTEMTYPE" section to the central util/sys_defs.h
include file.  You may have to invent new feature macro names.
Please choose sensible feature macro names such as HAS_DBM or
FIONREAD_IN_SYS_FILIO_H.

<p> I strongly recommend against using "#ifdef SYSTEMTYPE" in
individual source files.  While this may look like the quickest
solution, it will create a mess when newer versions of the same
SYSTEMTYPE need to be supported.  You're likely to end up placing
"#ifdef" sections all over the source code again.  </p>

<h2><a name="install">6 - Installing the software after successful
compilation</a></h2>

<p> This text describes how to install Postfix from source code.
See the PACKAGE_README file if you are building a package for
distribution to other systems. </p>

<h3>6.1 - Save existing Sendmail binaries</h3>

<p> <a name="save">IMPORTANT</a>: if you are REPLACING an existing
Sendmail installation with Postfix, you may need to keep the old
sendmail program running for some time in order to flush the mail
queue. </p>

<ul>

<li> <p> Some systems implement a mail switch mechanism where
different MTAs (Postfix, Sendmail, etc.) can be installed at the
same time, while only one of them is actually being used. Examples
of such switching mechanisms are the FreeBSD mailwrapper(8) or the
Linux mail switch.  In this case you should try to "flip" the switch
to "Postfix" before installing Postfix. </p>

<li> <p> If your system has no mail switch mechanism, execute the
following commands (your sendmail, newaliases and mailq programs
may be in a different place): </p>

<pre>
# mv /usr/sbin/sendmail /usr/sbin/sendmail.OFF
# mv /usr/bin/newaliases /usr/bin/newaliases.OFF
# mv /usr/bin/mailq /usr/bin/mailq.OFF
# chmod 755 /usr/sbin/sendmail.OFF /usr/bin/newaliases.OFF \
    /usr/bin/mailq.OFF
</pre>

</ul>

<h3>6.2 - Create account and groups</h3>

<p> Before you install Postfix for the first time you need to
create an account and a group:</p>

<ul>

<li> <p> Create a user account "postfix" with a user id and group
id that are not used by any other user account.  Preferably, this
is an account that no-one can log into.  The account does not need
an executable login shell, and needs no existing home directory.
My password and group file entries look like this: </p>

<blockquote>
<pre>
/etc/passwd:
    postfix:*:12345:12345:postfix:/no/where:/no/shell

/etc/group:
    postfix:*:12345:
</pre>
</blockquote>

<p> Note: there should be no whitespace before "postfix:". </p>

<li> <p> Create a group "postdrop" with a group id that is not used
by any other user account. Not even by the postfix user account.
My group file entry looks like:

<blockquote>
<pre>
/etc/group:
    postdrop:*:54321:
</pre>
</blockquote>

<p> Note: there should be no whitespace before "postdrop:". </p>

</ul>

<h3>6.3 - Install Postfix</h3>

<p> To install or upgrade Postfix from compiled source code, run
one of the following commands as the super-user:</p>

<blockquote>
<pre>
# make install       (interactive version, first time install)

# make upgrade       (non-interactive version, for upgrades)
</pre>
</blockquote>

<ul>

<li> <p> The interactive version ("make install") asks for pathnames
for Postfix data and program files, and stores your preferences in
the main.cf file. <b> If you don't want Postfix to overwrite
non-Postfix "sendmail", "mailq" and "newaliases" files, specify
pathnames that end in ".postfix"</b>. </p>

<li> <p> The non-interactive version ("make upgrade") needs the
/etc/postfix/main.cf file from a previous installation. If the file
does not exist, use interactive installation ("make install")
instead. </p>

<li> <p> If you specify name=value arguments on the "make install"
or "make upgrade" command line, then these will take precedence
over compiled-in default settings or main.cf settings. </p>

<p> The command "make install/upgrade name=value ..." will replace
the string MAIL_VERSION at the end of a configuration parameter
value with the Postfix release version. Do not try to specify
something like $mail_version on this command line. This produces
inconsistent results with different versions of the make(1) command.
</p>

</ul>

<h3>6.4 - Configure Postfix</h3>

<p> Proceed to the section on how you wish to run Postfix on
your particular machine: </p>

<ul>

<li> <p> <a href="#send_only">Send</a> mail only, without changing
an existing Sendmail installation (section 7). </p>

<li> <p> <a href="#send_receive">Send and receive</a> mail via a
virtual host interface, still without any change to an existing
Sendmail installation (section 8). </p>

<li> <p> Run Postfix <a href="#replace">instead of</a> Sendmail
(section 9). </p>

</ul>

<h2><a name="send_only">7 - Configuring Postfix to send mail
only</a></h2>

<p> If you are going to use Postfix to send mail only, there is no
need to change your existing sendmail setup. Instead, set up your
mail user agent so that it calls the Postfix sendmail program
directly. </p>

<p> Follow the instructions in the "<a href="#mandatory">Mandatory
configuration file edits</a>" in section 10, and review the "<a
href="#hamlet">To chroot or not to chroot</a>" text in section
11. </p>

<p> You MUST comment out the "smtp inet" entry in /etc/postfix/master.cf,
in order to avoid conflicts with the real sendmail. Put a "#"
character in front of the line that defines the smtpd service: </p>

<blockquote>
<pre>
/etc/postfix/master.cf:
    #smtp      inet  n       -       n       -       -       smtpd
</pre>
</blockquote>

<p> Start the Postfix system: </p>

<blockquote>
<pre>
# postfix start
</pre>
</blockquote>

<p> or, if you feel nostalgic, use the Postfix sendmail command: </p>

<blockquote>
<pre>
# sendmail -bd -qwhatever
</pre>
</blockquote>

<p> and watch your maillog file for any error messages. The pathname
is /var/log/maillog, /var/log/mail, /var/log/syslog, or something
else. Typically, the pathname is defined in the /etc/syslog.conf
file. </p>

<blockquote>
<pre>
$ grep -E '(reject|warning|error|fatal|panic):' /some/log/file
</pre>
</blockquote>

<p> Note: the most important error message is logged first. Later
messages are not as useful. </p>

<p> In order to inspect the mail queue, use one of the following
commands: </p>

<blockquote>
<pre>
$ mailq

$ sendmail -bp

$ postqueue -p
</pre>
</blockquote>

<p> See also the "<a href="#care">Care and feeding</a>" section 12
below.  </p>

<h2><a name="send_receive">8 - Configuring Postfix to send and
receive mail via virtual interface</a></h2>

<p> Alternatively, you can use the Postfix system to send AND
receive mail while leaving your Sendmail setup intact, by running
Postfix on a virtual interface address.  Simply configure your mail
user agent to directly invoke the Postfix sendmail program.  </p>

<p> To create a virtual network interface address, study your
system ifconfig manual page. The command syntax could be any
of: </p>

<blockquote>
<pre>
# <b>ifconfig le0:1 &lt;address&gt; netmask &lt;mask&gt; up</b>
# <b>ifconfig en0 alias &lt;address&gt; netmask 255.255.255.255</b>
</pre>
</blockquote>

<p> In the /etc/postfix/main.cf file, I would specify </p>

<blockquote>
<pre>
/etc/postfix/main.cf:
    myhostname = virtual.host.tld
    inet_interfaces = $myhostname
    mydestination = $myhostname
</pre>
</blockquote>

<p> Follow the instructions in the "<a href="#mandatory">Mandatory
configuration file edits</a>" in section 10, and review the "<a
href="#hamlet">To chroot or not to chroot</a>" text in section
11. </p>

<p> Start the Postfix system: </p>

<blockquote>
<pre>
# postfix start
</pre>
</blockquote>

<p> or, if you feel nostalgic, use the Postfix sendmail command: </p>

<blockquote>
<pre>
# sendmail -bd -qwhatever
</pre>
</blockquote>

<p> and watch your maillog file for any error messages. The pathname
is /var/log/maillog, /var/log/mail, /var/log/syslog, or something
else. Typically, the pathname is defined in the /etc/syslog.conf
file. </p>

<blockquote>
<pre>
$ grep -E '(reject|warning|error|fatal|panic):' /some/log/file
</pre>
</blockquote>

<p> Note: the most important error message is logged first. Later
messages are not as useful. </p>

<p> In order to inspect the mail queue, use one of the following
commands: </p>

<blockquote>
<pre>
$ mailq

$ sendmail -bp

$ postqueue -p
</pre>
</blockquote>

<p> See also the "<a href="#care">Care and feeding</a>" section 12
below.  </p>

<h2><a name="replace">9 - Running Postfix instead of Sendmail</a></h2>

<p> Prior to installing Postfix you should <a href="#save">save</a>
any existing sendmail program files as described in section 6.  Be
sure to keep the old sendmail running for at least a couple days
to flush any unsent mail. To do so, stop the sendmail daemon and
restart it as: </p>

<blockquote>
<pre>
# /usr/sbin/sendmail.OFF -q
</pre>
</blockquote>

<p> Note: this is old sendmail syntax. Newer versions use separate
processes for mail submission and for running the queue. </p>

<p> After you have visited the "<a href="#mandatory">Mandatory
configuration file edits</a>" section below, you can start the
Postfix system with: </p>

<blockquote>
<pre>
# postfix start
</pre>
</blockquote>

<p> or, if you feel nostalgic, use the Postfix sendmail command: </p>

<blockquote>
<pre>
# sendmail -bd -qwhatever
</pre>
</blockquote>

<p> and watch your maillog file for any error messages. The pathname
is /var/log/maillog, /var/log/mail, /var/log/syslog, or something
else. Typically, the pathname is defined in the /etc/syslog.conf
file. </p>

<blockquote>
<pre>
$ grep -E '(reject|warning|error|fatal|panic):' /some/log/file
</pre>
</blockquote>

<p> Note: the most important error message is logged first. Later
messages are not as useful. </p>

<p> In order to inspect the mail queue, use one of the following
commands: </p>

<blockquote>
<pre>
$ mailq

$ sendmail -bp

$ postqueue -p
</pre>
</blockquote>

<p> See also the "<a href="#care">Care and feeding</a>" section 12
below.  </p>

<h2><a name="mandatory">10 - Mandatory configuration file edits</a></h2>

<p> Note: the material covered in this section is covered in more
detail in the BASIC_CONFIGURATION_README document. The information
presented below is targeted at experienced system administrators.
</p>

<h3>10.1 - Postfix configuration files</h3>

<p> By default, Postfix configuration files are in /etc/postfix.
The two most important files are main.cf and master.cf; these files
must be owned by root.  Giving someone else write permission to
main.cf or master.cf (or to their parent directories) means giving
root privileges to that person. </p>

<p> In /etc/postfix/main.cf, you will have to set up a minimal number
of configuration parameters.  Postfix configuration parameters
resemble shell variables, with two important differences: the first
one is that Postfix does not know about quotes like the UNIX shell
does.</p>

<p> You specify a configuration parameter as: </p>

<blockquote>
<pre>
/etc/postfix/main.cf:
    parameter = value
</pre>
</blockquote>

<p> and you use it by putting a "$" character in front of its name: </p>

<blockquote>
<pre>
/etc/postfix/main.cf:
    other_parameter = $parameter
</pre>
</blockquote>

<p> You can use $parameter before it is given a value (that is the
second main difference with UNIX shell variables). The Postfix
configuration language uses lazy evaluation, and does not look at
a parameter value until it is needed at runtime.  </p>

<p> Whenever you make a change to the main.cf or master.cf file,
execute the following command in order to refresh a running mail
system: </p>

<blockquote>
<pre>
# postfix reload
</pre>
</blockquote>

<h3>10.2 - Default domain for unqualified addresses</h3>

<p> First of all, you must specify what domain will be appended to an
unqualified address (i.e. an address without @domain.tld). The
"myorigin" parameter defaults to the local hostname, but that is
probably OK only for very small sites.  </p>

<p> Some examples (use only one): </p>

<blockquote>
<pre>
/etc/postfix/main.cf:
    myorigin = $myhostname    (send mail as "user@$myhostname")
    myorigin = $mydomain      (send mail as "user@$mydomain")
</pre>
</blockquote>

<h3>10.3 - What domains to receive locally</h3>

<p> Next you need to specify what mail addresses Postfix should deliver
locally. </p>

<p> Some examples (use only one): </p>

<blockquote>
<pre>
/etc/postfix/main.cf:
    mydestination = $myhostname, localhost.$mydomain, localhost
    mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
    mydestination = $myhostname
</pre>
</blockquote>

<p>The first example is appropriate for a workstation, the second
is appropriate for the mailserver for an entire domain. The third
example should be used when running on a virtual host interface.</p>

<h3>10.4 - Proxy/NAT interface addresses </h3>

<p> The proxy_interfaces parameter specifies all network addresses
that Postfix receives mail on by way of a proxy or network address
translation unit. You may specify symbolic hostnames instead of
network addresses. </p>

<p> IMPORTANT: You must specify your proxy/NAT external addresses
when your system is a backup MX host for other domains, otherwise
mail delivery loops will happen when the primary MX host is down.
</p>

<p> Example: host behind NAT box running a backup MX host. </p>

<blockquote>
<pre>
/etc/postfix/main.cf:
    proxy_interfaces = 1.2.3.4 (the proxy/NAT external network address)
</pre>
</blockquote>

<h3>10.5 - What local clients to relay mail from </h3>

<p> If your machine is on an open network then you must specify
what client IP addresses are authorized to relay their mail through
your machine into the Internet.  The default setting includes all
subnetworks that the machine is attached to. This may give relay
permission to too many clients.  My own settings are: </p>

<blockquote>
<pre>
/etc/postfix/main.cf:
    mynetworks = 168.100.189.0/28, 127.0.0.0/8
</pre>
</blockquote>

<h3>10.6 - What relay destinations to accept from strangers </h3>

<p> If your machine is on an open network then you must also specify
whether Postfix will forward mail from strangers.  The default
setting will forward mail to all domains (and subdomains of) what
is listed in $mydestination.  This may give relay permission for
too many destinations.  Recommended settings (use only one): </p>

<blockquote>
<pre>
/etc/postfix/main.cf:
    relay_domains =            (do not forward mail from strangers)
    relay_domains = $mydomain  (my domain and subdomains)
    relay_domains = $mydomain, other.domain.tld, ...
</pre>
</blockquote>

<h3>10.7 - Optional: configure a smart host for remote delivery</h3>

<p> If you're behind a firewall, you should set up a relayhost.  If
you can, specify the organizational domain name so that Postfix
can use DNS lookups, and so that it can fall back to a secondary
MX host when the primary MX host is down. Otherwise just specify
a hard-coded hostname.  </p>

<p> Some examples (use only one): </p>

<blockquote>
<pre>
/etc/postfix/main.cf:
    relayhost = $mydomain
    relayhost = [mail.$mydomain]
</pre>
</blockquote>

<p> The form enclosed with <tt>[]</tt> eliminates DNS MX lookups. </p>

<p> By default, the SMTP client will do DNS lookups even when you
specify a relay host. If your machine has no access to a DNS server,
turn off SMTP client DNS lookups like this: </p>

<blockquote>
<pre>
/etc/postfix/main.cf:
    disable_dns_lookups = yes
</pre>
</blockquote>

<p> The STANDARD_CONFIGURATION_README file has more hints and tips for
firewalled and/or dial-up networks. </p>

<h3>10.8 - Create the aliases database</h3>

<p> Postfix uses a Sendmail-compatible aliases(5) table to redirect
mail for local(8) recipients.  Typically, this information is kept
in two files: in a text file /etc/aliases and in an indexed file
/etc/aliases.db.  The command "postconf alias_maps" will tell you
the exact location of the text file.  </p>

<p> First, be sure to update the text file with aliases for root,
postmaster and "postfix" that forward mail to a real person.  Postfix
has a sample aliases file /etc/postfix/aliases that you can copy
and adapt to local conditions.  /p>

<blockquote>
<pre>
/etc/aliases:
    root: you
    postmaster: root
    postfix: root
    bin: root
    <i>etcetera...</i>
</pre>
</blockquote>

<p> Note: there should be no whitespace before the ":". </p>

<p> Finally, build the indexed aliases file with one of the
following commands: </p>

<blockquote>
<pre>
# newaliases
# sendmail -bi
# postalias /etc/aliases (pathname is system dependent!)
</pre>
</blockquote>

<p> The form "postalias /etc/aliases" builds a default-type indexed
file. Use "postalias <i>type</i>:/etc/aliases" to specify an explicit
type (it should match the type in the output from "postconf -x
alias_maps"). </p>

<p> The default indexed file type is configured with the
default_database_type parameter. To list available explicit types,
execute the command "<b>postconf -m</b>".</p>

<h2><a name="hamlet">11 - To chroot or not to chroot</a></h2>

<p> Postfix daemon processes can be configured (via master.cf) to
run in a chroot jail.  The processes run at a fixed low privilege
and with access only to the Postfix queue directories (/var/spool/postfix).
This provides a significant barrier against intrusion. The barrier
is not impenetrable, but every little bit helps. </p>

<p> With the exception of Postfix daemons that deliver mail locally
and/or that execute non-Postfix commands, every Postfix daemon can
run chrooted. </p>

<p> Sites with high security requirements should consider to chroot
all daemons that talk to the network:  the smtp(8) and smtpd(8)
processes, and perhaps also the lmtp(8) client. The author's own
porcupine.org mail server runs all daemons chrooted that can be
chrooted. </p>

<p> The default /etc/postfix/master.cf file specifies that no
Postfix daemon runs chrooted.  In order to enable chroot operation,
edit the file /etc/postfix/master.cf. Instructions are in the file.
</p>

<p> Note that a chrooted daemon resolves all filenames relative to
the Postfix queue directory (/var/spool/postfix). For successful
use of a chroot jail,  most UNIX systems require you to bring in
some files or device nodes.  The examples/chroot-setup directory
in the source code distribution has a collection of scripts that
help you set up Postfix chroot environments on different operating
systems. </p>

<p> Additionally, you almost certainly need to configure syslogd
so that it listens on a socket inside the Postfix queue directory.
Examples for specific systems: </p>

<dl>

<dt> FreeBSD: </dt>

<dd> <pre>
# mkdir -p /var/spool/postfix/var/run
# syslogd -l /var/spool/postfix/var/run/log
</pre> </dd>

<dt> Linux, OpenBSD: </dt>

<dd> <pre>
# mkdir -p /var/spool/postfix/dev
# syslogd -a /var/spool/postfix/dev/log
</pre> </dd>

</dl>

<h2><a name="care">12 - Care and feeding of the Postfix system</a></h2>

<p> Postfix daemon processes run in the background, and log problems
and normal activity to the syslog daemon. The names of logfiles
are specified in /etc/syslog.conf. At the very least you need
something like:  </p>

<blockquote>
<pre>
/etc/syslog.conf:
    mail.err                                    /dev/console
    mail.debug                                  /var/log/maillog
</pre>
</blockquote>

<p> IMPORTANT: the syslogd will not create files. You must create
them before (re)starting syslogd. </p>

<p> IMPORTANT: on Linux you need to put a "-" character before
the pathname, e.g., -/var/log/maillog, otherwise the syslogd
will use more system resources than Postfix does. </p>

<p> Hopefully, the number of problems will be small, but it is a good
idea to run every night before the syslog files are rotated: </p>

<blockquote>
<pre>
# postfix check
# grep -E '(reject|warning|error|fatal|panic):' /some/log/file
</pre>
</blockquote>

<ul>

<li> <p> The first line (postfix check) causes Postfix to report
file permission/ownership discrepancies. </p>

<li> <p> The second line looks for problem reports from the mail
software, and reports how effective the relay and junk mail access
blocks are.  This may produce a lot of output.  You will want to
apply some postprocessing to eliminate uninteresting information.
</p>

</ul>

<p>  The <a href="DEBUG_README.html#logging"> DEBUG_README </a>
document describes the meaning of the "warning" etc. labels in
Postfix logging. </p>

</body>

</html>