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<html>
<head>
<title> Postfix Configuration - Basics </title>
</head>
<body>
<h1><a href="big-picture.html"><img src="small-picture.gif" width="115" height="45"></a> Postfix Configuration - Basics </h1>
<hr>
<a href="index.html">Up one level</a> | Basic Configuration | <a
href="uce.html">UCE Controls</a> | <a href="rate.html"> Rate
Controls</a> | <a href="resource.html"> Resource Controls</a> | <a
href="rewrite.html"> Address Manipulation </a>
<h2> Introduction </h2>
Postfix has about 100 configuration parameters that are controlled
via the <b>main.cf</b> file. Fortunately, they have sensible
default values. In most cases, you need to configure only two or
three parameters before you can use the Postfix mail system:
<ul>
<li> <a href="#myorigin"> What domain to use in outbound mail </a>
<p>
<li> <a href="#mydestination"> What domains to receive mail for
</a>
</ul>
The default values for many other configuration parameters are
derived from just these two.
<p>
The third parameter of interest controls the amount of mail sent
to the local postmaster:
<ul>
<li> <a href="#notify"> What trouble to report to the postmaster
</a>
</ul>
<p>
By the way, if you change parameters of a running Postfix system,
don't forget to issue a <b>postfix reload</b> command.
<p>
If you run Postfix on a virtual network interface, or if your
machine runs other mailers on virtual interfaces, you'll have to
look at the other parameters listed here as well:
<ul>
<li> <a href="#myhostname"> My own hostname </a>
<p>
<li> <a href="#mydomain"> My own domain name </a>
<p>
<li> <a href="#mynetworks"> My own networks </a>
<p>
<li> <a href="#inet_interfaces"> My own network addresses </a>
</ul>
<a name="myorigin"> <h2> What domain to use in outbound mail </h2> </a>
The <b>myorigin</b> parameter specifies the domain that appears in
mail that is posted on this machine. The default is to use the
local machine name, <b><a href="#myhostname"> $myhostname</a>, </b>
which defaults to the name of the machine. Unless you are running
a really small site, you probably want to change that into <b><a
href="#mydomain"> $mydomain</a>,</b> which defaults to the parent
domain of the machine name.
<p>
<dl>
<dt> Examples:
<p>
<dd> <b>myorigin = $myhostname</b> (default)
<dd> <b>myorigin = $mydomain</b> (probably desirable)
</dl>
<a name="mydestination"> <h2> What domains to receive mail for
</h2> </a>
The <b>mydestination</b> parameter specifies what domains this
machine will deliver locally, instead of forwarding to another
machine. The default is to receive mail for the machine itself.
<p>
You can specify zero or more domain names, <i>/file/name</i> patterns
and/or <i>type:name</i> lookup tables, separated by whitespace
and/or commas. A <i>/file/name</i> is replaced by its contents;
<i>type:name</i> requests that a table lookup is done, typically
from a <a href="rewrite.html#virtual">virtual</a> database.
<p>
If your machine is a mail server for its entire domain, you must
list <b>$mydomain</b> as well.
<p>
<dl> Examples:
<p>
<dl>
<dt> Default setting:
<dd> <b>mydestination = $myhostname localhost.$mydomain</b>
<p>
<dt> Domain-wide mail server:
<dd> <b>mydestination = $myhostname localhost.$mydomain $mydomain
</b>
<p>
<dt> Host with multiple DNS A records:
<dd> <b>mydestination = $myhostname localhost.$mydomain www.$mydomain
ftp.$mydomain</b>
</dl>
<p>
Caution: in order to avoid mail delivery loops, you must list all
hostnames of the machine, including $myhostname, and localhost.$mydomain.
</dl>
<a name="notify"> <h2> What trouble to report to the postmaster
</h2> </a>
You should set up a <b>postmaster</b> <a
href="rewrite.html#aliases">alias</a> that points to a human person.
This alias is required to exist, so that people can report mail
delivery problems.
<p>
The Postfix system itself also reports problems to the postmaster
alias. You may not be interested in all types of trouble reports,
so this reporting mechanism is configurable. The default is to
report only serious problems (resource, software) to postmaster:
<p>
<dl>
<dt> Default:
<dd> <b>notify_classes = resource, software</b>
<p>
<dt>The meaning of the classes is as follows:
<p>
<dl>
<dt> <b>bounce</b> <dd> Send postmaster copies of undeliverable
mail. If mail is undeliverable, a so-called single bounce message
is sent, with a copy of the message that was not delivered. For
privacy reasons, the postmaster copy of a single bounce message is
truncated after the original message headers. If a single bounce
message is undeliverable, the postmaster receives a double bounce
message with a copy of the entire single bounce message. See also
the <a href="rewrite.html#luser_relay"> luser_relay</a> feature.
<p>
<dt> <b>2bounce</b> <dd> Send double bounces to the postmaster.
<p>
<dt> <b>delay</b> <dd> Inform the postmaster of delayed mail.
In this case, the postmaster receives message headers only.
<p>
<dt> <b>policy</b> <dd> Inform the postmaster of client requests
that were rejected because of (UCE) policy restrictions. The
postmaster receives a transcript of the entire SMTP session.
<p>
<dt> <b>protocol</b> <dd> Inform the postmaster of protocol errors
(client or server side) or attempts by a client to execute
unimplemented commands. The postmaster receives a transcript of
the entire SMTP session.
<p>
<dt> <b>resource</b> <dd> Inform the postmaster of mail not delivered
due to resource problems (for example, queue file write errors).
<p>
<dt> <b>software</b> <dd> Inform the postmaster of mail not delivered
due to software problems.
</dl>
</dl>
<a name="myhostname"> <h2> My own hostname </h2> </a>
The <b>myhostname</b> parameter describes the fully-qualified domain
name of the machine running the Postfix system. <b> $myhostname</b>
appears as the default value in many other Postfix configuration
parameters.
<p>
By default, <b>myhostname</b> is set to the local machine name.
If your machine name is not in fully-qualified domain name form,
or if you run Postfix on a virtual interface, you will have to
specify the fully-qualified domain name that the mail system
should use.
<dl>
<dt> Examples:
<p>
<dd> <b>myhostname = host.local.domain</b> (local hostname is not
FQDN)
<dd> <b>myhostname = host.virtual.domain</b> (virtual interface)
<dd> <b>myhostname = virtual.domain</b> (virtual interface)
</dl>
<a name="mydomain"> <h2> My own domain name </h2> </a>
The <b>mydomain</b> parameter specifies the parent domain of
<b>$myhostname.</b> By default it is derived from <b> $myhostname</b>
by stripping off the first part (unless the result would be a
top-level domain).
<dl>
<dt> Examples:
<p>
<dd> <b>mydomain = local.domain</b>
<dd> <b>mydomain = virtual.domain</b> (virtual interface)
</dl>
<a name="mynetworks"> <h2> My own networks </h2> </a>
The <b>mynetworks</b> parameter lists all networks that this machine
is attached to. This information can be used by the <a href="uce.html">
anti-UCE</a> features to distinguish between local systems and
strangers.
<p>
By default, <b>mynetworks</b> is set to the class A, B or C networks
that the machine is attached to. For example, for my machines at
home, the result is: <b>168.100.0.0/16 127.0.0.0/8. </b> However,
network <b>168.100</b> is owned by my ISP. Of course I do not want
to consider all their customer systems as local, so I use instead:
<dl>
<dd> <b>mynetworks = 168.100.189.0/28, 127.0.0.0/8</b>
</dl>
<a name="inet_interfaces"> <h2> My own network addresses </h2> </a>
The <b>inet_interfaces</b> parameter specifies all network interface
addresses that the Postfix system should listen on; mail addressed
to <i>user</i>@[<i>network address</i>] will be delivered locally,
as if it is addressed to a domain listed in <b> $mydestination.
</b>
<p>
The default is to listen on all active interfaces. If you run
mailers on virtual interfaces, you will have to specify what
interfaces to listen on. This includes the non-virtual mailer that
receives mail for the machine itself as well: it should never listen
on the virtual interfaces or you would have a mailer loop.
<dl>
<dt> Examples:
<p>
<dl>
<dt> Default:
<dd> <b>inet_interfaces = all</b>
<p>
<dt> Host running virtual mailers:
<dd> <b>inet_interfaces = virtual.host.name</b> (virtual domain)
<dd> <b>inet_interfaces = $myhostname localhost.$mydomain</b>
(non-virtual mailer)
</dl>
</dl>
<hr>
<a href="index.html">Up one level</a> | Basic Configuration | <a
href="uce.html">UCE Controls</a> | <a href="rate.html"> Rate
Controls</a> | <a href="resource.html"> Resource Controls</a> | <a
href="rewrite.html"> Address Manipulation </a>
</body>
</html>
|
